# Multiple Voltage Question



## DarkLore (Jan 25, 2009)

I'm working on a prop that will use household current, a prop controller, an audio controller, a kit made-circuit board, a series of relays, etc. There are different circuits in the prop and the boards all have different input voltage requirements. Not counting the household circuit inside the prop, there are required inputs of 12vdc, 9v, and 5v.

Two of the controllers run 12vdc and could share a pigtailed input. Is there a premade/sold pigtail that takes one wall wart adapter and splits it into two? If not, what's the best way to solder one up?

Is there any kind of cheap and small step down regulator or something to pull 9v and/or 5v from 12v? Note - I'm dumb as a rock and I'm not an electrician. Please provide simple and detailed explanations if you can. I'm not looking for cat5 wiring to a source. I simply want to reduce the number of wall warts I'm using. I don't like the thought of having 4 wall wart cords out the back end of this thing.


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## randyaz (May 26, 2006)

http://www.radioshack.com/product/index.jsp?productId=2062599
http://www.radioshack.com/product/index.jsp?productId=2062600
http://www.radioshack.com/product/index.jsp?productId=2062601


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## hedg12 (Jul 6, 2008)

Do you know how much current you'll be needing from the 9v and 5v supplies? The easiest way I know would be to use LM7809 & LM7805 regulators. They are simple 3 connector TO220 package devices - you put +12v on one pin, ground on another, and get either +9v (LM7809) or +5v (LM7805) from the third pin. They can only handle about 1 amp max, though.

edit: man, I'm just too slow today!


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## DarkLore (Jan 25, 2009)

randyaz said:


> http://www.radioshack.com/product/index.jsp?productId=2062599
> http://www.radioshack.com/product/index.jsp?productId=2062600
> http://www.radioshack.com/product/index.jsp?productId=2062601


randaz...Remember the dumb as a rock part? How do I use them? (Let's say I wanted to bring in a lone 12vdc, 1500ma, with two pigtailed plugs for the controllers. How do I wire these in?)

hedg12 - One of the boards (9v) is a chaser kit from All Electronics. Basically a 555 timer card that sequences 10 leds.

I need the 5v to power a USB plasma ball. (Another question...will the EMF from the plasma ball interfere with other circuits? I'm not sure how much distance I have yet.)


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## hedg12 (Jul 6, 2008)

I'm assuming (bad idea, I know) that this is the LED chaser kit you're talking about. It should be fine with the LM7809.

The LM78XX regulators have 3 connections - a voltage in, a voltage out, and a ground. To use them, hook both voltage inputs to +12 volts from your wall wart, and both grounds to the negative (ground) connection of your wart. Just run a wire from each, and tie them together. Then, connect the voltage out from the 7809 to the + voltage in (the red wire of the 9v battery clip that comes with the kit) and another wire from the ground connection of your wart to the negative connection (black wire on the battery clip.) Do the same from the 7805 to the power connections on the plasma ball (it is a usb device - does it have a power connection other than the usb plug?) As long as the current draw of all the items you're running doesn't exceed 1500 milliamps, you're golden. I don't imagine the LED chaser kit draws more than 40 - 50 milliamps, and the USB spec doesn't allow for more than 500 milliamps, so that leaves you with just under 1 amp available for your other controllers. You'll probably want to use some kind of heatsink on the regulators - they can get a little hot.

The RF emission from the plasma ball is at a pretty high frequency, so I doubt you'll have any issues with it.

Have you ever thought of powering all this with a PC power supply? They're cheap, simple to modify, and would give you the power and voltages you need without mucking around with the regulators (the LED chaser kit will work on anything from 3 to 9 volts, so you could power it from the 5 volt output of the PS.) Just a thought.


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## DarkLore (Jan 25, 2009)

Thanks. Yall's input has been very helpful. I did a bit of reading...which showed me exactly what you are describing. Thanks for the tip on the heatsink.










Yes, the plasma ball has a short USB to mini plug cable....and it has a center positive mini plug.

A PC power supply would just be one more thing to mess with...and bulky. The reason for my questions is not just to reduce the number...but to possibly contain the wall wart(s) within the prop itself. This would leave me a single external plug to the household current. With the information you have provided...it should be a piece of cake.


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## hedg12 (Jul 6, 2008)

Cool. Can't wait to see the finished product!


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## hpropman (Jul 27, 2008)

you can also use a computer power supply which already has 5 and 12 volt outputs then you can add a 7809 for the 9 volt supply. You can sometimes find them at curbys. Anytime you see a computer in the trash grab it for the power supply.


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## hpropman (Jul 27, 2008)

you can get thre 7809 at Jameco.com and MPJA.com


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## pshort (May 6, 2008)

The datasheets for the regulator usually recommend adding one capacitor between the input to the regulator and ground (0.33 μF would be a good choice), as well as another one between the regulator output and ground (0.1 μF). WIthout these caps there is some risk that the regulator will oscillate or do other bad things.

Look at page 22 of this spec:

http://www.fairchildsemi.com/ds/LM/LM7805A.pdf


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## hpropman (Jul 27, 2008)

when a make one of these circuits I add a 220uF Electrolytic to the input if the circuit will be powering a motor or servo. If no motor then I add a 100uf electrolytic to the input. On the output I normally place a 47Uf electrolytic and a .1uf and then .01uf to the power leads of any chip in the circuit. Here is the circuit the diode on the input is for reverse polarity protection an IN4001 will work fine. also not that electrolytic caps have polarity and must be connected in the correct orientation (the negative lead is normally marked on them). See the second picture. If you have any more questions please ask. There is also a free electronics course in the links section of my website.


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## DarkLore (Jan 25, 2009)

Capacitors. Check.


I have several spare PC power supplies but I generally don't like the bulkiness, air flow problems or weight. I'd prefer to use a single 12vdc 1500 ma adapter..inside the case. But now that I think about it - there will be three pneumatic valves going off the 12v output of the controller. So I may need to reconsider.


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## DarkLore (Jan 25, 2009)

Hmm...must have missed that part where I mentioned that I was dumb as a rock. I wasn't kidding. I'm only 3 pts shy of slobbering on myself.


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## hpropman (Jul 27, 2008)

one step at a time and ask as many questions as you need to. Do not rush this


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## DarkLore (Jan 25, 2009)

I intend to post a diagram and probably a photo before I power up anything that has to do with regulators. I suspect it will be a few days before I can get to the electronics store again.

I'm currently held up on a design issue dealing with the front of the prop.


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## hedg12 (Jul 6, 2008)

The smoothing caps certainly wouldn't hurt but I doubt you'd need them, given what you plan to run off the regulators. If you want to keep it simple, you might try it without them. You can always add them later if you get any wierdness in the LED chaser or plasma ball.

Edit: Scratch that - sorry, just saw that you're running air solenoids off the same 12v tap. You'll probably need the caps. You might be pushing the current limits of the wall wart, too.


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## DarkLore (Jan 25, 2009)

hpropman said:


> one step at a time and ask as many questions as you need to. Do not rush this


I'm not going to pursue it. I enjoy building props, not circuit boards. There isn't enough aesthetic value for me to go to the trouble of including this stuff in the prop.


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## fritz42_male (May 5, 2009)

I use a 12V supply from DealExtreme and some little variable voltage regulator boards that I used to get from Dick Smith Electronics (RadioShack elsewhere)

Link is here. Hope it's of use - someone may know where these can be found in the US

http://www.dse.com.au/cgi-bin/dse.storefront/4b727cfc02923da42744c0a87e0106e0/Product/View/K3594

The 12V 5A PSU from DealExtreme is excellent - plenty of grunt for the Windscreen Wiper kits, only $17 and universal input voltage. Link here:

http://www.dealextreme.com/details.dx/sku.15993


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## DarkLore (Jan 25, 2009)

With some additional assistance from hedg12, I did build a regulator circuit. But due to the record breaking snowstorm preventing me from leaving the house, I had to use the parts I managed to find at R/S or had available to me.

The following is what I created - a 5vdc regulator circuit based on the 7805. The image is labeled with input of 9-12vdc, but I understand the input could be higher.










Here's my illustration for non-circuit designers -










Radio Shack sells most of these parts...at a premium price. If you were to look at my board from underneath, it's a masterful piece of art.










My soldering is so wonderful, you couldn't tell mine from one built by advanced robotics. Okay maybe mine looks like it was soldered with hot coals and a stick the size of one of those big red pencils they used to give out in kindergarten...but it does works. (If you don't know the pencils I'm talking about, ask gramps. If you do...sorry hear it old timer. How's your prostate?)

I plug a rough 12vdc wall wart into the thing, and I get a clean 5.00 vdc output. I don't know if this is what I was supposed to do...but it does what I set out to do. Thanks yall.


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## paulcav151 (Nov 15, 2009)

Darklore: Why the 2 capacitors on the output from the 7805?


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## DarkLore (Jan 25, 2009)

I reviewed the information provided by others on the thread. Using that information as a starting point, I searched the net for some circuit diagrams to better understand what hedg and hpropman were describing to me.

I found a circuit designed like the one I built, that called for a non-polarized (100n) capacitor. The same type of circuit appeared in many references - each recommended slight differences. I couldn't find that 100n part at R/S, but I had extra components already in hand for other projects. I understood I could use the ceramic 0.1uF as a replacement to that. The addition of the capacitors are to smooth out the fluctuations in voltage and filter out stray voltage spikes.


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## hedg12 (Jul 6, 2008)

Darklore, sorry to go off topic, but what program do you use for your diagrams?


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## DarkLore (Jan 25, 2009)

I'm working on a two part project - a pneumatic Frankenstein monster and desktop controller prop. My original question relates to a need in my controller prop. (see image in the sticky - Use of Prop Controllers).

The controller contains two cards - an EZ-8 (12vdc) and an audio board (input 4.5-12vdc). The EZ-8 is controlling a series of relays. Four of the relays will control the monster's pneumatic valves, and led eyes. Two more relays will switch 110 outlets on the back of the prop to turn on warning lights and ambient mood lights (possibly green lighting instead of the red flasher indicated in my sketch). Another relay will trigger a fog machine. And the last relay will trigger one sound clip on the audio card.










Not shown in the diagram:

Four light sockets across the top are wired to an internal 110 dimmer switch to give the look of glowing lab lights (25w appliance bulbs)...similar to vacuum tubes. Six push buttons on the front of the prop will trigger six more sound clips by normally open contact. The front will contain 10 sequencing leds. And two very large meters - wired to light off the 110 circuit.

And finally, a front panel mounted plasma ball that normally runs off a PC computer's usb port (5v). The reason for my original question - I want to drive the plasma ball using the 12v wall wart that will power my prop controller.


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## DarkLore (Jan 25, 2009)

The inside of the controller prop currently looks like this...










The back looks like this...










The ugly stains are there because I was touching up the screws to make them look old. Unfortunately the stain layers didn't match and instead of blending, it just looks like streak marks. No big deal...it's the back of the prop. Exposed on the back are the connectors I will use to attach the pneumatics, the led eyes, and the fogger. The outlets are activated by the prop controller. Visible in the center area is the dimmer switch for the top lighting.

My intent is to trigger the prop when someone walks up near the monster. It may say something aloud like "Please do not let the monster smell your candy." A first set of red warning flashers is triggered, and the audio will continue with an alarm sound. Then the lights will flip to green ambient and fog will trigger as the monster starts to growl. At that point, the monster might say something like, "I smell candy. I smell children. Arrggrrrr." At this point, the pneumatics sequentially fire as the monster growls and moves to break free from the table straps, reaches out, or whatever I decide.

But the overall problem....how to combine those different circuits to use the fewest number of adapters and plugs, while still maintaining enough power to manage the activity.


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## DarkLore (Jan 25, 2009)

hedg12 said:


> Darklore, sorry to go off topic, but what program do you use for your diagrams?


I use a vector drawing program called CorelDraw. Similar to Adobe Illustrator. My version is probably older than some of the folks viewing the thread.


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## hedg12 (Jul 6, 2008)

DarkLore said:


> I use a vector drawing program called CorelDraw. Similar to Adobe Illustrator. My version is probably older than some of the folks viewing the thread.


Cool, thanks.

Again, can't wait to see this prop in action.


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## paulcav151 (Nov 15, 2009)

I understand the concept of a capacitor, at the beginning of the circuit to filter the input, and at the end to filter the output. Your diagram showsa .1uf, and a 10uf on the output end. Are you saying they are substitutes for each other, and only one or the other should be used, and you are only showing them both as an illustration, or are both necessary in the circuit to produce the desired output?


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## fritz42_male (May 5, 2009)

CorelDraw was my favourite as well. Not impressed with the current version - I think it was V8 that I last used.


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## DarkLore (Jan 25, 2009)

Sorry paulcav151, I must not have explained that well. Go to the link below and find the diagram labeled Power Supplies - Fixed.

POWER SUPPLIES - FIXED:

The diagram calls for a 100n capacitor on both sides of the 7805 - no implicit polarity (plus/minus). I didn't have the part and neither did Radio Shack when I was out looking the evening before I created the circuit. Due to more than foot of snow in Dallas, no snow plows in sight, and a driveway steeper than college tuition increases...I couldn't get to an electronic parts store. So I made use of what I had. I used a 0.1 ceramic on the output side as a substitute for the 100n, non-polarizing capacitor. (I understand the regulator would work without them, but it's preferable to have them.)

The illustration represents what I made (without drawing a heatsink on the 7805, because it would obscure the view of the other parts). This circuit gives me a very steady 5vdc from a 12vdc wall adapter.


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## hedg12 (Jul 6, 2008)

paulcav151 said:


> I understand the concept of a capacitor, at the beginning of the circuit to filter the input, and at the end to filter the output. Your diagram showsa .1uf, and a 10uf on the output end. Are you saying they are substitutes for each other, and only one or the other should be used, and you are only showing them both as an illustration, or are both necessary in the circuit to produce the desired output?


The caps are in the circuit to filter out voltage spikes and noise. The smaller lower uF caps respond more quickly to voltage changes and filter out higher frequency noise. The larger higher uF caps target lower frequency spikes, and provide a small amount of "smoothing" by buffering the current flow (very small in this case - probably insignificant.)


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## hpropman (Jul 27, 2008)

hedg12 said:


> The caps are in the circuit to filter out voltage spikes and noise. The smaller lower uF caps respond more quickly to voltage changes and filter out higher frequency noise. The larger higher uF caps target lower frequency spikes, and provide a small amount of "smoothing" by buffering the current flow (very small in this case - probably insignificant.)


exactly correct - the smaller .01uf caps are more for noise that can affect a microcontroller or a chip. I also add a .01uf cap to all chips as close to the power leads as possible. These ensure that the circuit operates as expected without any strange behavior from voltage fluctuations. Having extra caps will never hurt a circuit. I just went and took a look at the prop1 documentation (I do not have one) for comparison He has a least 3 electrolytic caps on his board and what looks like several surface mount caps (probably .01uf caps). The main purpose of these caps is to make the circuit run stable and not be affected by a sudden change in voltage. Just think of them a small batteries that will release some of there power to keep the voltage at the proper level if it starts to drop. You will also hear them referred to as filters. There are some very good electronics websites out there that will teach you electronics for free. There is a nice one in the links section of my website. even just the basics will help you understand a great deal of what happens when we use a prop controller. Also I noticed the Radio Shack is again selling the book getting started in electronics which is probable the best beginning book that I have ever read. Mine is over 25 years old with yellowing pages. Maybe I will pick up a new one for my son.


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## paulcav151 (Nov 15, 2009)

Thanks for clearing that up guys. I am interested in this thread because I would like to convert my laser swirling vortex to be powered with a 12vdc 500ma walwart. The motor is a 12vdc cooling fan, and the laser is 3vdc. I am thinking I can run the fan directly (or with a capacitor), and run the laser using an adjustable voltage regulator (317T i think). Am I in the ballpark?


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## hpropman (Jul 27, 2008)

I would run the fan directly from the 12V wall wart no cap needed and noise will not affect the motor at all. I would make a separate power supply based on LM317T for the 3 volt supply. any 6-9 volt DC wall wart should be fine for that and would add the caps also. This link may be helpful to you.

LM317 - Wikipedia, the free [email protected]@[email protected]@/wiki/File:LM317_1A_ConstCurrent.jpg" class="image"><img alt="" src="http://upload.wikimedia.org/wikipedia/commons/thumb/b/bb/LM317_1A_ConstCurrent.jpg/180px-LM317_1A_ConstCurrent.jpg"@@[email protected]@commons/thumb/b/bb/LM317_1A_ConstCurrent.jpg/180px-LM317_1A_ConstCurrent.jpg


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## paulcav151 (Nov 15, 2009)

I was hoping to not have to run 2 wall warts to it. Do you recommend I not use the 12vdc to power both?


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## hpropman (Jul 27, 2008)

two reasons why I recommend that you use two. One the adapter is only 500ma and I do not know how much current the fan will use if you have a meter maybe you can measure it. Also the fan will generate a lot of noise that may or may not affect the laser pointer. I have not yet played with laser pointers so I can be positive. I was erring on the side of caution so that you do not have any problems with power or noise. Can you do it with one adapter yes but check how much power that fan will use first. Also you will need some caps in the LM317T circuit if you use one adapter for both. I would add a 220uf Electrolytic to the input of the voltage regulator and something like a 47uf Electrolytic and a .01uf ceramic to the output. I know that the LM317T has better stability then the 780X regulators but I would still add the caps. If the fan current is more than 300ma then I would consider getter a more powerful adapter like a 1amp. You really never want to tax the wall warts past half there current capacity it shortens their lives. A good rule of thumb is that you want to have a least twice as much current then is needed. It does need mean that you will use the current. the circuit will only use what it needs the rest is overhead safety margin and longevity of the circuit.


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## paulcav151 (Nov 15, 2009)

I found the specs on the laser. It needs min/max 150/250mA of current. I also looked at similar fans and found them to be 300+mA, which, as you surmised, would be too much for my 500mA wall wart. Thank you so much for your help on this. You saved me from excess work building the regulator circuit, and a fried wall wart. I will take your rec and use separate wall warts.


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## DarkLore (Jan 25, 2009)

hedg12 said:


> Cool, thanks.
> 
> Again, can't wait to see this prop in action.


The guts of this prop got quite a bit more complicated than the photos referenced in this thread due to the front panel connections. I haven't decided whether I'll do anything more to the front of the prop. I tossed a few of my original plans in order to add more dimension depth to the whole front (the gauges were a bit daunting). The lights on the top of the prop are controlled by a dimmer. In the photos they are turned down.

Anyway...these images should give an idea of the prop and its size.


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## DarkLore (Jan 25, 2009)

*Monster Controller Video Clip*

Video Clip


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## fritz42_male (May 5, 2009)

That looks sooooo good Darklore.

Steampunk Superb!


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## hpropman (Jul 27, 2008)

Wow very nice! Looks like something similar I have in mind this year for my electric chair. Is that one of those mini lightning storms above the switches? Also How did you do the glowing tubes on top and where did you get those buttons and meters? I have collected a bunch of ceramic insulators and some nice sound clips already. I also just got a nice large knife switch off ebay to electrocute my guest and take a picture.


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## fritz42_male (May 5, 2009)

Yes, I agree I'd like to know where the parts came from as well. Nice use of a Plasma Ball.


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## hedg12 (Jul 6, 2008)

That is awesome! Turned out so cool - love it! Those antique meters are perfect - really add to the look. Great job.

Did you decide against the LED chaser, or am I missing it?

It's warming up enough now that I can get off the couch and back into the shop, & this is great inspiration. Time to get busy!


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## DarkLore (Jan 25, 2009)

hpropman said:


> Wow very nice! Looks like something similar I have in mind this year for my electric chair. Is that one of those mini lightning storms above the switches? Also How did you do the glowing tubes on top and where did you get those buttons and meters? I have collected a bunch of ceramic insulators and some nice sound clips already. I also just got a nice large knife switch off ebay to electrocute my guest and take a picture.


So you are the one that got the knife switch? I got busy when the last few went off and didn't put in a final bid. lol

The plasma ball is called a usb plasma ball. I needed the voltage regulator to power it from the 12v source.

The lights on the top are 25w appliance bulbs from HDepot. They require an adapter to use regular sockets. I did this so I can swap bulbs if I choose a different type. They are wired to a wall dimmer switch in the back of the prop.

The red buttons and switches can be purchased at All Electronics. They are also available from some electronics store.

The meters are from an old locomotive. I removed the guts and put them on a shelf...just in case I ever need to run that many volts..lol. To light them up, I built lighted bases with c7 lights running through the prop's 110 wiring.


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## fritz42_male (May 5, 2009)

I light the idea of a light chaser but with steampunk stuff, you want incandescents rather than LED.


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## Arris138 (Apr 24, 2010)

Going back to the wiring diagram to step down the voltage, what would be necessary to step down 24v to 12v? I picked up some of the 7812's that should do the trick, but apparently there needs to be maybe a different capacitor layout, since as soon as I tried it with the 24v 1.5A the transistor burned up and cracked. The circuit works fine with 12v 1A in and a 7805, so i'm guessing it has something to do with the smaller cap.


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## pshort (May 6, 2008)

Perhaps.

But it's more likely that it is dissipating too much power. Without a heat sink it is not good long term for more than about 1W. With 12V across the regulator (24V - 12V) you shouldn't push more than about 0.1A through it. You would need a really good heatsink if you are really trying to push 1.5A through the part for any amount of time.


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## DarkLore (Jan 25, 2009)

What about using something like one of these step down converters?


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## hedg12 (Jul 6, 2008)

Depending on what you're doing, you could just build a simple voltage divider circuit.










The bad thing about this is that it's pretty inefficient & draws current constantly. Bad idea if you're using batteries. What are you trying to run off 12 volts?


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## pshort (May 6, 2008)

hedge,

Arris' device is drawing enough current so that the regulator released it's magic smoke, so I don't think that voltage divider circuit is going to work. While I've never used it, I think that the thing in darklore's post will have much better chances of working.


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## hedg12 (Jul 6, 2008)

I agree that it wouldn't be the best bet - just looking at options. For $12, the d.c. - d.c. converter is probably the way to go.

Still curious about what he's running off the circuit.


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## GhoulishGadgets (May 13, 2010)

Hi,

The reason the smoke was released was the input voltage was too high, although the datasheet would probably say its ok. Trying to drop a higher input-output voltage differential and supply significant current means lots of heat will be generated - with no heatsink, then bye-bye regulator within a few seconds.

just to explain, say you're output is running at 12v 1A, then the regulator needs to lose the other 12v (input-output voltage difference), the power dissipated would be P=IV, so 1A x 12v = 12W needing to be lost... heat is the only way... that's a decent amount of heat for that little device.

maybe using a LM317 may be better, they're quite tolerant of higher input voltages, are very similar to 78xx devices, just add a few resistors (see datasheet, easy to sort) - but use a heatsink and heatsink compound.

I'm unsure what package you're using, I'd go for what is known as the TO3 - this is metal, one connection is the casing and has 2 pins, searching for the datasheet will show this - these are better for these higher dissipation applications.

Si


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## GhoulishGadgets (May 13, 2010)

Duplicate post, sorry


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## Arris138 (Apr 24, 2010)

Thanks a bunch for the info. I actually had a small heat sink attached to it and still it burned up in a few seconds. The reason i'm going this route is I got a few 24v power transformers used in security systems that would make life quite easy to wire up most of my props, since they have 16 separate circuits and fuses. If I can get it to step down to 12v, I could wire 90% props to 2 separate hubs, and use a mix of 24v and 12v.

At the time I was testing the circuit, I didn't even have anything hooked up to the leads, I was just going using my multimeter to check the voltage. I'll try GhoulishGadget's advice and step up the transformer and get a better heatsink on it to try to dissipate the heat. After checking the datasheet on these transformers, they're pushing 2-4A, so i'm thinking they may be too hot to try and step down safely.


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## Arris138 (Apr 24, 2010)

Also, Darklore have you used those step downs? I can't really tell what sort of outputs it has on it, so not really sure how it'd work in my setup.


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## pshort (May 6, 2008)

Probably a dumb question, but does the 'power transformers' have an AC or DC output? If the output is AC, you have to convert it to DC before it goes to the regulator.


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## DarkLore (Jan 25, 2009)

Arris138 said:


> Also, Darklore have you used those step downs? I can't really tell what sort of outputs it has on it, so not really sure how it'd work in my setup.


I haven't used them. My submission of this thread was the first time I had a need to combine voltages in a single prop.


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## hedg12 (Jul 6, 2008)

Arris138 said:


> Thanks a bunch for the info. I actually had a small heat sink attached to it and still it burned up in a few seconds. The reason i'm going this route is I got a few 24v power transformers used in security systems that would make life quite easy to wire up most of my props, since they have 16 separate circuits and fuses. If I can get it to step down to 12v, I could wire 90% props to 2 separate hubs, and use a mix of 24v and 12v.
> 
> At the time I was testing the circuit, I didn't even have anything hooked up to the leads, I was just going using my multimeter to check the voltage. I'll try GhoulishGadget's advice and step up the transformer and get a better heatsink on it to try to dissipate the heat. After checking the datasheet on these transformers, they're pushing 2-4A, so i'm thinking they may be too hot to try and step down safely.


Most security system transformers I've come across are A.C., which would wreak havoc with the regulator circuit. The fact that it burned up without anything connected to the output of the regulator would indicate a wiring problem or wrong input voltage (or A.C. on the input.).


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