Simple DC voltage doubler

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Potato Cakes

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Hello, Everyone,

I am trying to double the voltage of a single source +24V switch mode PSU to do phantom power as well. The schematic I found online for doing this only seems to output the same as the input. It does indeed say it is for DC

https://www.electronics-tutorials.ws/blog/voltage-multiplier-circuit.html

I even did the tripler circuit and was able to get 30V but not where it is labeled as V out, so something is not right. I would appreciate being pointed in the right direction if someone would be as so kind.

Thanks!

Paul
 

Potato Cakes

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I also found this. It looks like its for AC to DC as well but it's labeled as either or as the first example was. However this does not work for DC-DC as I am getting 22VDC where I am expecting 2Vout.

I believe what I'm experiencing is bad information on the internet...
 

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Potato Cakes

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abbey road d enfer

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Potato Cakes said:
I also found this. It looks like its for AC to DC as well but it's labeled as either or as the first example was. However this does not work for DC-DC as I am getting 22VDC where I am expecting 2Vout.

I believe what I'm experiencing is bad information on the internet...
Typical lesson given by one who doesn't know the subject.
 

JohnRoberts

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Potato Cakes said:
Hello, Everyone,

I am trying to double the voltage of a single source +24V switch mode PSU to do phantom power as well. The schematic I found online for doing this only seems to output the same as the input. It does indeed say it is for DC

https://www.electronics-tutorials.ws/blog/voltage-multiplier-circuit.html

I even did the tripler circuit and was able to get 30V but not where it is labeled as V out, so something is not right. I would appreciate being pointed in the right direction if someone would be as so kind.

Thanks!

Paul
Standard voltage doublers grab AC from the mains transformer.

If you have access to the innards of the switching PS you could literally grab a high frequency square wave from that circuit to feed a cap doubler/tripler.

Note: if switching at 100kHz you don't need as large of a capacitor as when switching at 120 Hz. I made a low current phantom supply this way a couple decades ago using tiny 0.1uf SMD caps and small signal diodes.

If the switching supply is sealed, or you don't want to mess with the innards (probably a good idea), you could roll your own AC with a simple square wave oscillator (555 timers were popular for this last century).

Probably easier to hang a low current 24V switching supply riding on top of the existing 24V output.

JR
 

Potato Cakes

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JohnRoberts said:
Standard voltage doublers grab AC from the mains transformer.

If you have access to the innards of the switching PS you could literally grab a high frequency square wave from that circuit to feed a cap doubler/tripler.

Note: if switching at 100kHz you don't need as large of a capacitor as when switching at 120 Hz. I made a low current phantom supply this way a couple decades ago using tiny 0.1uf SMD caps and small signal diodes.

If the switching supply is sealed, or you don't want to mess with the innards (probably a good idea), you could roll your own AC with a simple square wave oscillator (555 timers were popular for this last century).

Probably easier to hang a low current 24V switching supply riding on top of the existing 24V output.

JR

The SMPS is enclosed but not sealed, so I do have access to the circuit. However, I'd rather not mess with it. This particular build as quite a bit crammed in it and it doesn't particularly need +48V. If I do I think at this point I'll just find a small 48V PSU and use that, I'm just annoyed that I can't seem to figure out an elegant way to power to handle different needs (single, bipolar, different voltages) in the same build. This has been the struggle for me with my builds.

Thanks!

Paul
 

Rochey

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I think I have something up my sleeve that could help with this...

(See attached image)

I need someone to prototype this in a system. Drop me a PM here or through Facebook (expat audio page there...)

Cheers

Rochey
 

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Dualflip

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Bo Deadly

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Potato Cakes said:
I'm just annoyed that I can't seem to figure out an elegant way to power to handle different needs (single, bipolar, different voltages) in the same build. This has been the struggle for me with my builds.
Getting a wide variety of voltages for all of the different possible circuits in analog audio is one of the more difficult issues with diy builds. Common requirements are +15, -15, +48, +24 and +5. And of course there are popular circuits that have special requirements like +30 and -10 for the 1176.

What I did was put a bunch of SMPS in an enclosure with some LC filtering on a PCB with 2 PCB mount 9 pin CPC connectors. Then I made cables to supply 4 different voltages and 2 grounds over a custom cable. Then, within each project enclosure, I regulate down to make each voltage required. This is also a little more efficient because you're only pulling what current the local circuit needs across the regulator. Meaning you could regulate 48V down to 30V for an 1176, for example, and not worry so much about wasting power / generating heat. So from 4-5 different base voltages, you can make just about anything you could possibly need (minus tube stuff which is a different animal entirely).
 

Potato Cakes

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squarewave said:
Getting a wide variety of voltages for all of the different possible circuits in analog audio is one of the more difficult issues with diy builds. Common requirements are +15, -15, +48, +24 and +5. And of course there are popular circuits that have special requirements like +30 and -10 for the 1176.

What I did was put a bunch of SMPS in an enclosure with some LC filtering on a PCB with 2 PCB mount 9 pin CPC connectors. Then I made cables to supply 4 different voltages and 2 grounds over a custom cable. Then, within each project enclosure, I regulate down to make each voltage required. This is also a little more efficient because you're only pulling what current the local circuit needs across the regulator. Meaning you could regulate 48V down to 30V for an 1176, for example, and not worry so much about wasting power / generating heat. So from 4-5 different base voltages, you can make just about anything you could possibly need (minus tube stuff which is a different animal entirely).

The one method I had thought about doing is getting a 48V PSU with a high enough amp rating and then use voltage dividers/drop resistors to get the voltages I needed for the various circuits. Since power supplies design and comprehension is a great struggle for me, I always assume my approach is the hard way and what I do can and should be simplified significantly.

I'll do some more messing around with this and see what I come up with. I honestly think it's just going to come down to simplifying the power requirements of the circuits being used.

Thanks!

Paul
 

JohnRoberts

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Potato Cakes said:
The one method I had thought about doing is getting a 48V PSU with a high enough amp rating and then use voltage dividers/drop resistors to get the voltages I needed for the various circuits. Since power supplies design and comprehension is a great struggle for me, I always assume my approach is the hard way and what I do can and should be simplified significantly.

I'll do some more messing around with this and see what I come up with. I honestly think it's just going to come down to simplifying the power requirements of the circuits being used.

Thanks!

Paul
Simple but using pass regulators to drop everything down from 48V will dissipate more heat... that said a few switchers for the higher current supplies would be efficient.

JR
 

Bo Deadly

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Potato Cakes said:
The one method I had thought about doing is getting a 48V PSU with a high enough amp rating and then use voltage dividers/drop resistors to get the voltages I needed for the various circuits. Since power supplies design and comprehension is a great struggle for me, I always assume my approach is the hard way and what I do can and should be simplified significantly.
While you can do that (as I have as I explained), you need to be cognizant of ohms law and power.

Take my 1176 example of making 30V from 48V. I dedicated a regulator for just that one circuit in that one project and it didn't implement the line output. So the current consumed from the regulator way maybe 50mA. So that means I'm dropping 48 - 30 = 18V at 50mA across the regulator. In terms of power that 0.05 * 18 = 0.9 watts. That's no problem for an LM317 even without a heatsink.

However, if you tried to drop say 48V down to 24V to power a pair of Neve circuits including the line outputs which runs ~70mA of DC through the OT IIRC, that's 48 - 24 * ~0.2 = 4.8W which would quickly burn out an LM317 even with a decent heat sink.
 

Potato Cakes

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squarewave said:
While you can do that (as I have as I explained), you need to be cognizant of ohms law and power.

Take my 1176 example of making 30V from 48V. I dedicated a regulator for just that one circuit in that one project and it didn't implement the line output. So the current consumed from the regulator way maybe 50mA. So that means I'm dropping 48 - 30 = 18V at 50mA across the regulator. In terms of power that 0.05 * 18 = 0.9 watts. That's no problem for an LM317 even without a heatsink.

However, if you tried to drop say 48V down to 24V to power a pair of Neve circuits including the line outputs which runs ~70mA of DC through the OT IIRC, that's 48 - 24 * ~0.2 = 4.8W which would quickly burn out an LM317 even with a decent heat sink.

With testing I have used a resistor to drop voltage from 48V to 24V for a 1073 type circuit and that required a 5W resistor. However I hadn't thought about double checking the wattage rating for a regulator if going that route.

Thanks!

Paul
 

Bo Deadly

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Using a resistor divider won't work anyway since the voltage will depend on how much current is being drawn (ohms law again). You would need to at least put a transistor or two after it.
 

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