Hi all.
I had this idea for a 300V supply, for say something using tubes or even in the KV range.
This is very simple, but I haven't seen much of it around (maybe I just haven't looked enough?). Assuming that the transistor is within its limits, is this practical?
It could also be used for say, an avalanche pulser, though you would probably use a switching supply for this in order to use a cheaper transformer.
As an afterthought, if the base current for the cascode affects accuracy too much, we need only drive it with an FET off of a 9V supply.
Also, DC accuracy is not guaranteed unless you adjust with a potentiometer and even then any drift will be amplified by about 120. As better solution would be perhaps to use an adjustable Zener+BJT, but we might be trading accuracy for lower accuracy.
- keantoken
I had this idea for a 300V supply, for say something using tubes or even in the KV range.
This is very simple, but I haven't seen much of it around (maybe I just haven't looked enough?). Assuming that the transistor is within its limits, is this practical?
It could also be used for say, an avalanche pulser, though you would probably use a switching supply for this in order to use a cheaper transformer.
As an afterthought, if the base current for the cascode affects accuracy too much, we need only drive it with an FET off of a 9V supply.
Also, DC accuracy is not guaranteed unless you adjust with a potentiometer and even then any drift will be amplified by about 120. As better solution would be perhaps to use an adjustable Zener+BJT, but we might be trading accuracy for lower accuracy.
- keantoken
Attachments
I found this for use with Nixie tubes but I hear works well with Other tubes ....
http://www.ledsales.com.au/kits/nixie_supply.pdf
Puts out 170v DC from 12v AC (so you can use the same Xformer for Plate and heater) and I believe you can get more voltage by useing a bigger inductor and Caps....
CHeers
http://www.ledsales.com.au/kits/nixie_supply.pdf
Puts out 170v DC from 12v AC (so you can use the same Xformer for Plate and heater) and I believe you can get more voltage by useing a bigger inductor and Caps....
CHeers
This is a strange switching supply I designed (simulated, haven't built yet). I had this crazy idea and it worked... Not sure how it compares to the others, but it doesn't need no 555, just throw it together out of spare parts.
Q3 improves efficiency, but it can be troublesome and isn't needed for the functionality of the circuit.
- keantoken
Q3 improves efficiency, but it can be troublesome and isn't needed for the functionality of the circuit.
- keantoken
Attachments
Good try, keantoken.
I recommend a fairly high voltage precision Voltage reference
and using VbE multiplying technique
you can get a very good high voltage regulatort.
TL431 is one 30 Volt volt precision adjustable zener-diode.
Very low price/performance! is another benefit.
The TL431 output voltage can be filtered RC, to improve parameters
if you need.
30V x 5 = 150 Volt, for example
Assisted with TO126 or TO220 transistor to cope with power=heat
Hi-volt-reg_120v
_lineup2006
Preferably Like my article for some years ago:
http://www.diyaudio.com/forums/showthread.php?postid=1567768#post1567768
Why re-invent everything when somebody already did some good work
to re.-construct The Wheel
Regards
your
Lineup of sweden
I recommend a fairly high voltage precision Voltage reference
and using VbE multiplying technique
you can get a very good high voltage regulatort.
TL431 is one 30 Volt volt precision adjustable zener-diode.
Very low price/performance! is another benefit.
The TL431 output voltage can be filtered RC, to improve parameters
if you need.
30V x 5 = 150 Volt, for example
Assisted with TO126 or TO220 transistor to cope with power=heat
Hi-volt-reg_120v
_lineup2006
Preferably Like my article for some years ago:
http://www.diyaudio.com/forums/showthread.php?postid=1567768#post1567768
Why re-invent everything when somebody already did some good work
to re.-construct The Wheel
Regards
your
Lineup of sweden
keantoken,
Here are a few comments on the circuits you posted.
Regarding the first one:
1. The circuit should work, but the 115k resistor needs to be increased to 295k to get an output voltage of 300 volts.
2. The base current of the transistor may cause significant error in the output voltage (depending on the current gain), therefore, I would use a MOSFET as you suggested. I would bias the gate of the MOSFET at around 10 volts.
3. The raw DC supply voltage should be a little higher, say 315 volts, to allow for component tolerances.
4. Using 315 volts and assuming the maximum output current is 1 mA, I would increase R4 to 5K. (This is not a big deal.)
5. What is the cap for? Any noise on the raw DC supply will be coupled directly to the TL431 sense pin and upset the output. You might want to connect the cap from the sense pin to ground.
6. You may have stability problems with this circuit.
The second circuit you posted is called a boost mode DC to DC converter. Here are some comments.
1. The output voltage will be highly dependent on the parameters (Is and Bf) of Q4, and will not be very accurate with different devices of the same type. This is because Is and Bf vary significantly from device to device. You need to use a better error amplifier.
2. The 180 uA current source will charge the gate capacitance of M1 very slowly. This means that is will switch slowly and there will be significant switching losses. You need a better gate drive circuit.
3. Many IC vendors (including LTC) make boost controllers that will far outperform a discrete circuit. If you really want to make such a circuit, consider them.
Rick
Here are a few comments on the circuits you posted.
Regarding the first one:
1. The circuit should work, but the 115k resistor needs to be increased to 295k to get an output voltage of 300 volts.
2. The base current of the transistor may cause significant error in the output voltage (depending on the current gain), therefore, I would use a MOSFET as you suggested. I would bias the gate of the MOSFET at around 10 volts.
3. The raw DC supply voltage should be a little higher, say 315 volts, to allow for component tolerances.
4. Using 315 volts and assuming the maximum output current is 1 mA, I would increase R4 to 5K. (This is not a big deal.)
5. What is the cap for? Any noise on the raw DC supply will be coupled directly to the TL431 sense pin and upset the output. You might want to connect the cap from the sense pin to ground.
6. You may have stability problems with this circuit.
The second circuit you posted is called a boost mode DC to DC converter. Here are some comments.
1. The output voltage will be highly dependent on the parameters (Is and Bf) of Q4, and will not be very accurate with different devices of the same type. This is because Is and Bf vary significantly from device to device. You need to use a better error amplifier.
2. The 180 uA current source will charge the gate capacitance of M1 very slowly. This means that is will switch slowly and there will be significant switching losses. You need a better gate drive circuit.
3. Many IC vendors (including LTC) make boost controllers that will far outperform a discrete circuit. If you really want to make such a circuit, consider them.
Rick
Thank you for your comments.
I wasn't thinking about accuracy when I designed the second circuit. If I made it in real life I would use an FET for the voltage sensing transistor and if not at least use a pot to trim the voltage to the desired value.
One of these days I will get around to trying to make a boost circuit that is good enough for tubes so that I can experiment.
My reasons for using C1 in the first circuit were to decrease the impedance of R3 and R1, so that any parasitic properties of the TL431 wouldn't interfere with the voltage sensing. I suppose we don't need this unless we are using a transistor as the voltage sensor.
Thanks,
- keantoken
I wasn't thinking about accuracy when I designed the second circuit. If I made it in real life I would use an FET for the voltage sensing transistor and if not at least use a pot to trim the voltage to the desired value.
One of these days I will get around to trying to make a boost circuit that is good enough for tubes so that I can experiment.
My reasons for using C1 in the first circuit were to decrease the impedance of R3 and R1, so that any parasitic properties of the TL431 wouldn't interfere with the voltage sensing. I suppose we don't need this unless we are using a transistor as the voltage sensor.
Thanks,
- keantoken
Hey, can someone tell me a good method for discharging 200V caps?
I'm experimenting with a circuit similar the second one I posted with a photoflash cap and have been discharging the "fun" way, but that's getting a little old.
I don't have any High-voltage, high-watt resistors.
My ears appreciate your suggestions.
Thanks,
- keantoken
P.S. I have realized that making a good discrete DC booster is harder than it looks, so I'm going to try and make my own 555 circuit. I might still try a discrete one after this one is done.
I'm experimenting with a circuit similar the second one I posted with a photoflash cap and have been discharging the "fun" way, but that's getting a little old.
I don't have any High-voltage, high-watt resistors.
My ears appreciate your suggestions.
Thanks,
- keantoken
P.S. I have realized that making a good discrete DC booster is harder than it looks, so I'm going to try and make my own 555 circuit. I might still try a discrete one after this one is done.
I think I prefer starting with high voltage.
Then regulate down and filter.
To start with low voltage and generate higher is a lot more tricky.
And will often limit the power you can generate in an easy way.
There are special transformers in a wellsorted audio/valve internet shops.
Intended for TUBE circuits, in the first place.
But also to isolate AC MAINS from the power supply.
230VAC in - 2 x 115 VAC out. And similar higher secondaries.
Take your pick if you want to rectify
at 230x1.4 VDC or 1.4 x 115 VDC (parallell secondary)
----
Another trick is to use two standard transformers.
For example two 230 VAC in - 2 x 24 VAC out
and them you connect them
Mains-> 230VAC:48VAC ---> 48VAC:230VAC -> output
and so you have 230x1.4 VDC after rectifier bridge.
By using, combining one 230-2x24 and one 230-2x18VAC
you can get other output than 230 VAC
/lineup advice on transformer tricks
Then regulate down and filter.
To start with low voltage and generate higher is a lot more tricky.
And will often limit the power you can generate in an easy way.
There are special transformers in a wellsorted audio/valve internet shops.
Intended for TUBE circuits, in the first place.
But also to isolate AC MAINS from the power supply.
230VAC in - 2 x 115 VAC out. And similar higher secondaries.
Take your pick if you want to rectify
at 230x1.4 VDC or 1.4 x 115 VDC (parallell secondary)
----
Another trick is to use two standard transformers.
For example two 230 VAC in - 2 x 24 VAC out
and them you connect them
Mains-> 230VAC:48VAC ---> 48VAC:230VAC -> output
and so you have 230x1.4 VDC after rectifier bridge.
By using, combining one 230-2x24 and one 230-2x18VAC
you can get other output than 230 VAC
/lineup
advice on transformer tricks
I have a transformer like the ones you describe, but I don't want to mess with mains wiring just yet.
I would rather build a boost circuit, which should be less dangerous.
I will need heatshrink tubing before I start messing with mains wiring.
I had a boostup circuit on the simulator that was working well, but I still had some kinks to work out. I will have to remake it, because LTSpice saved a blank file - which it does when you have run out of disk space because of all the .raw files for your simulation data.
- keantoken
I would rather build a boost circuit, which should be less dangerous.
I will need heatshrink tubing before I start messing with mains wiring.
I had a boostup circuit on the simulator that was working well, but I still had some kinks to work out. I will have to remake it, because LTSpice saved a blank file - which it does when you have run out of disk space because of all the .raw files for your simulation data.
- keantoken
Well, if you are able, you do it your way
.. I do it my better way.
Anyway I cant stop you
Even if I really want to .. this time only, keantoken
----
Yes, it has happened for me. too .. several times
when I loose my MultiSim work because the program is out of memory.
Best thing then, is to as quickly as possible try to re-create your circuit
.. while is fresh in your mind & more Human Memory
regars
your lineup
.. I do it my better way.
Anyway I cant stop you
Even if I really want to .. this time only, keantoken
----
Yes, it has happened for me. too .. several times
when I loose my MultiSim work because the program is out of memory.
Best thing then, is to as quickly as possible try to re-create your circuit
.. while is fresh in your mind & more Human Memory
regars
your lineup
Why is one high voltage more dangerous than another.
What you are up against is introducing some oscillation
to create, build up some current injections into coils.
Such other higher frequencies we usually avoid inside a box for Audio.
One reason to keep computers and amplfiers seperate.
There are exceptions to this.
Like in the Class-D amplifiers around today.
One common place to find voltage boosters, is in Car Power supplies.
They need it for to get more voltage/power into them 4 Ohms speakers.
Have you looked into these forums, Searched:
- Class-D digital amps
- Car Audio
What you are up against is introducing some oscillation
to create, build up some current injections into coils.
Such other higher frequencies we usually avoid inside a box for Audio.
One reason to keep computers and amplfiers seperate.
There are exceptions to this.
Like in the Class-D amplifiers around today.
One common place to find voltage boosters, is in Car Power supplies.
They need it for to get more voltage/power into them 4 Ohms speakers.
Have you looked into these forums, Searched:
- Class-D digital amps
- Car Audio
lineup said:
I would gues the differance between a High Voltage high current transformer and a High Voltage Low current switching supply is well , the high current, which at these Voltages is pretty lethal .....
I"ve used the Back 2 Back 12v Transformer method for tube supplies and it works pretty well and its pretty safe if you are carefull....
Cheers
It is the current that paralyses takes out heart/brain.
True.
Otherwise we would be all dead .. by static electricity.
Even stroking a cat would put your life at riscue
On the other hand .. we need voltage to produce currents.
Which means, that if the conductance is high enough and the resistence is low enough
than any voltage can kill you .. if you are in bad luck some fine day.
True.
Otherwise we would be all dead .. by static electricity.
Even stroking a cat would put your life at riscue
On the other hand .. we need voltage to produce currents.
Which means, that if the conductance is high enough and the resistence is low enough
than any voltage can kill you .. if you are in bad luck some fine day.
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