opcom,
The only 110VDC gear I ever saw was my brothers Philco AM 4 tube radio with 3-way power
(90VDC battery + 1.5V or 3V battery; 110VAC; and 110VDC).
Parallel resistors for a bleeder is a pretty good idea.
The problem with bleeder resistors is that you can get carried away.
Suppose you have an amplifier B+ filter that is CRCRCRC.
Which C do you put the parallel bleeder resistors across?
What if one of the 3 Rs in that B+ filter burns out, then one end or the other of that filter chain will not be bled down.
So you use 8 bleeder resistors just to be safe?
I use resistors that have power ratings of 5X the power that will be in them. They run cooler, and are less likely to fail.
The only 110VDC gear I ever saw was my brothers Philco AM 4 tube radio with 3-way power
(90VDC battery + 1.5V or 3V battery; 110VAC; and 110VDC).
Parallel resistors for a bleeder is a pretty good idea.
The problem with bleeder resistors is that you can get carried away.
Suppose you have an amplifier B+ filter that is CRCRCRC.
Which C do you put the parallel bleeder resistors across?
What if one of the 3 Rs in that B+ filter burns out, then one end or the other of that filter chain will not be bled down.
So you use 8 bleeder resistors just to be safe?
I use resistors that have power ratings of 5X the power that will be in them. They run cooler, and are less likely to fail.
I'm a long-term electronics hobbyist getting started on tube amps. Boy this thread is giving me anxiety - this is terrifying! Good info, though. I'd rather be scared, and careful, than injured or dead.
I just picked up a 15w amp with a dead transformer (apparently). Waiting for my variac and parts to build a bulb limiter and capacitor draining leads, and then I'll pull and test that transformer. Wish me luck!
I just picked up a 15w amp with a dead transformer (apparently). Waiting for my variac and parts to build a bulb limiter and capacitor draining leads, and then I'll pull and test that transformer. Wish me luck!
I can attest 500+V hurts! Being one of the few that don't seem to learn very fast I have hit myself good 3 times with 500V+. Once thru both hands. Luckily didn't do a thing to me but hurt. I did however blow a hole in my arm once and bled all over the place. From a shock..!!
Bleed resistors save lives.... Use them.
Bleed resistors save lives.... Use them.
Can I use a DC to DC converter 12VDC to 300 VDC to generate the high voltage for a tube preamp?
Something like this: DC DC V 8 ~ V 32 V to 45 ~ 390 V Adjustable high voltage boost converter zvs Step up Booster Module capacitor charge board|Switching Power Supply| - AliExpress
The amplifier I want to build requires 12.6V heater voltage + 285V high voltage (I assume DC) So I want to use a 12 VDC 2A adapter + this DC to DC converter to drive the whole amplifier. Maybe add a Soft Start function. Or a timer, so that the Heater voltage lets the tubes heat up before they get the high voltage from the DC to DC converter.
Is this a doable solution?
Something like this: DC DC V 8 ~ V 32 V to 45 ~ 390 V Adjustable high voltage boost converter zvs Step up Booster Module capacitor charge board|Switching Power Supply| - AliExpress
The amplifier I want to build requires 12.6V heater voltage + 285V high voltage (I assume DC) So I want to use a 12 VDC 2A adapter + this DC to DC converter to drive the whole amplifier. Maybe add a Soft Start function. Or a timer, so that the Heater voltage lets the tubes heat up before they get the high voltage from the DC to DC converter.
Is this a doable solution?
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Yes you can. I've done it many times. The one you linked is a noisy piece of crap though.
No soft start is necessary, no timer either...
This kind is much better, and it's isolated to you can use it for a negative supply (bias) if you want, too.
DC-AC Converter 12V to 110V 200V 220V 280V 150W Inverter Boost Board Transformer | eBay
Also 12V 2A will be too small to even light up the heaters because they don't like starting into cold heaters... Go with at least 5A, preferrably 10A.
https://www.amazon.ca/100-240V-Adapter-Converter-Transformer-5-5x2-1mm/dp/B07NV6N5QS/
No soft start is necessary, no timer either...
This kind is much better, and it's isolated to you can use it for a negative supply (bias) if you want, too.
DC-AC Converter 12V to 110V 200V 220V 280V 150W Inverter Boost Board Transformer | eBay
Also 12V 2A will be too small to even light up the heaters because they don't like starting into cold heaters... Go with at least 5A, preferrably 10A.
https://www.amazon.ca/100-240V-Adapter-Converter-Transformer-5-5x2-1mm/dp/B07NV6N5QS/
Excellent 
Thank you so much for your fast reply!
For some reason the seller you linked to does not ship to Sweden. I think I found some similar, or identical on Ali Express:
DC AC Converter 12V to 110V 200V 220V 280V 150W Inverter Boost Board Transformer|Inverters & Converters| - AliExpress or this:
150W MC Converter DC 12V To AC 220V Inverter Boost Transformer Power Board Module High Frequency Square Wave AC Output 20KHz|Replacement Parts & Accessories| - AliExpress
The second one seems to have more output voltage options.
I wonder if it is possible to connect the outputs in series to get exactly the voltage one needs?
V0--V2=110V
V0--V3=175V
V0--V4=200V
V0--V5=220V
V5--V4=20V
V5--V3=45V
V5--V2=110V
V4--V3=28V
V4--V2=90V
V3--V2=62V
Thank you so much for your fast reply!For some reason the seller you linked to does not ship to Sweden. I think I found some similar, or identical on Ali Express:
DC AC Converter 12V to 110V 200V 220V 280V 150W Inverter Boost Board Transformer|Inverters & Converters| - AliExpress or this:
150W MC Converter DC 12V To AC 220V Inverter Boost Transformer Power Board Module High Frequency Square Wave AC Output 20KHz|Replacement Parts & Accessories| - AliExpress
The second one seems to have more output voltage options.
I wonder if it is possible to connect the outputs in series to get exactly the voltage one needs?
V0--V2=110V
V0--V3=175V
V0--V4=200V
V0--V5=220V
V5--V4=20V
V5--V3=45V
V5--V2=110V
V4--V3=28V
V4--V2=90V
V3--V2=62V
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Alternative?
This converter has AC output, but besides that it looks similar to the model you used, right?
150W Booster Board Inverter Module Step up Transformer DC 12V to AC 220V Power Inverter Charger Converter Boost Board|Transformers| - AliExpress
That particular seller ships this model from Germany - another EU country - so I would not have to pay import duties nor VAT, a big advantage.
I hope I can connect it like a regular AC output from a standard transformer and build the power supply for a Marantz 7C clone using a silicone rectifier bridge and capacitors? Do you think I can skip the capacitors for the tube heaters? Simply connect them directly to 12V DC stabilized power from the 12v 8A adapter?
See attached schematic I found on YouTube
I just found 3pcs 12v 8A power supplies in my closet
This converter has AC output, but besides that it looks similar to the model you used, right?
150W Booster Board Inverter Module Step up Transformer DC 12V to AC 220V Power Inverter Charger Converter Boost Board|Transformers| - AliExpress
That particular seller ships this model from Germany - another EU country - so I would not have to pay import duties nor VAT, a big advantage.
I hope I can connect it like a regular AC output from a standard transformer and build the power supply for a Marantz 7C clone using a silicone rectifier bridge and capacitors? Do you think I can skip the capacitors for the tube heaters? Simply connect them directly to 12V DC stabilized power from the 12v 8A adapter?
See attached schematic I found on YouTube
Attachments
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It's similar. Different transformer so you'll need a Delon doubler, and usually these switch at 20kHz where the DC one I linked is set for 37kHz.
As shown you can't use it in that schematic because there's no 520VCT output hence the Delon doubler (Full wave)
Otherwise you can do whatever you want but use fast diodes like HER208 or similar. 1N4007 will fail shorted.
If you tell me how many volts you need for your preamp, I can knock something together as an example.
As shown you can't use it in that schematic because there's no 520VCT output hence the Delon doubler (Full wave)
Otherwise you can do whatever you want but use fast diodes like HER208 or similar. 1N4007 will fail shorted.
If you tell me how many volts you need for your preamp, I can knock something together as an example.
Voltages
I found a schematic on YouTube, see my previous, edited post, but I may buy this board/kit on Ali:
SUQIYA PRT07A tube preamplifier finished board reference Marantz 7 circuit|Amplifier| - AliExpress
or this McIntosh C22 variant:
Tube Amplifier Preamp PRT03A Tube Preamplifier Board DIY Kits C22 Electric Circuit 068|Amplifier| - AliExpress
They both seem to require 280 VDC and 12.6 VDC.
Not sure why they write 280 VDC, Two groups, though.. In the schematic they just added resistors for voltage drops to the three valves. Do you understand why they specify Two groups? Would I need Two of the DC to AC converters?
I found a schematic on YouTube, see my previous, edited post, but I may buy this board/kit on Ali:
SUQIYA PRT07A tube preamplifier finished board reference Marantz 7 circuit|Amplifier| - AliExpress
or this McIntosh C22 variant:
Tube Amplifier Preamp PRT03A Tube Preamplifier Board DIY Kits C22 Electric Circuit 068|Amplifier| - AliExpress
They both seem to require 280 VDC and 12.6 VDC.
Not sure why they write 280 VDC, Two groups, though.. In the schematic they just added resistors for voltage drops to the three valves. Do you understand why they specify Two groups? Would I need Two of the DC to AC converters?
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Not sure why they write 280 VDC, Two groups, though.. In the PREVIOUS schematic they just added resistors for voltage drops to the three valves. Do you understand why they specify Two groups for the kits? Would I need Two of the DC to AC converters?
This guy in this chinese article:
彷制马兰士 Marantz 7 M7 胆前级放大器 | TTRadio
uses 40 7.5V Zener diodes in series to regulate the voltage, see attached pic:
This guy in this chinese article:
彷制马兰士 Marantz 7 M7 胆前级放大器 | TTRadio
uses 40 7.5V Zener diodes in series to regulate the voltage, see attached pic:
Attachments
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You can the the above schematic, but replace two of the diodes with 470uF 250V capacitors and go from the 175V output (this will give you nearly the same voltages at in the above pic you attached...
Here's an example of the Delon. Not the right values for you, but you see how it works. With your square wave input, RMS becomes 0.5x peak so this makes 175x2=350V. If the above example below was square wave, the output voltage would be closer to 230V
Here's an example of the Delon. Not the right values for you, but you see how it works. With your square wave input, RMS becomes 0.5x peak so this makes 175x2=350V. If the above example below was square wave, the output voltage would be closer to 230V
Attachments
Thanks for the schematic!
Three big capacitors, one even bigger and special diodes are all required to get the Delon to work?
I think I will go for the model you recommended first, and pay import duties, after all.
I just wish there were smaller converters that could do the trick. The tubes only require 280 VDC @20 mA, efter all.
Three big capacitors, one even bigger and special diodes are all required to get the Delon to work?
I think I will go for the model you recommended first, and pay import duties, after all.
I just wish there were smaller converters that could do the trick. The tubes only require 280 VDC @20 mA, efter all.
I am not very skilled in high voltage designs, the Delon looks a bit intimidating. I wish there was a simpler way to create 280VC 50mA (for some headroom) from 12VDC.
And the heaters in my preamp only require 0.8A.
It would be so cool to be able to run a tube preamp from a wall wart!
This guy has a solution but the voltage is 210 VDC @ 9 VDC input. I wonder if it scales after the input voltage? :http://www.hagtech.com/pdf/cornet3.pdf
On page 7 there is a schematic for the DC 9V to DC 210 V converter for a three tube phono preamp.
And the heaters in my preamp only require 0.8A.
It would be so cool to be able to run a tube preamp from a wall wart!
This guy has a solution but the voltage is 210 VDC @ 9 VDC input. I wonder if it scales after the input voltage? :http://www.hagtech.com/pdf/cornet3.pdf
On page 7 there is a schematic for the DC 9V to DC 210 V converter for a three tube phono preamp.
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Ok, what are the numbers for this three tube preamp, please? And could I do with the other diode you mentioned, the HER208 if I only need, say 50 mA? (some headroom)
I downloaded PSUDUD and got stuck when it did not list the HER208 under diodes.
Have you tested this little guy:
12V to 220V Step UP Power Module 35W DC-AC Boost Inverter Module Dual Channel | eBay
This guy did:
Royer Oscillator Inverter with Output Capacitive Dropper - YouTube
Playing with: 12V DC to 220V AC Inverter Royer Oscillator - YouTube
Have you tested this little guy:
12V to 220V Step UP Power Module 35W DC-AC Boost Inverter Module Dual Channel | eBay
This guy did:
Royer Oscillator Inverter with Output Capacitive Dropper - YouTube
Playing with: 12V DC to 220V AC Inverter Royer Oscillator - YouTube
Good to know about these DC-DC boards! Very handy
If you are in a hurry and if you don't mind some different voltage, you can use a "DC-AC" china el-cheapo small converter, and delete the 60Hz fake seno output ("modified" square wave making parts), using only the DC-DC stage. These converters are sometimes very cheap and are easy to obtain in some places
I made the PSU for my car tube amp using one of these converters.
If you are in a hurry and if you don't mind some different voltage, you can use a "DC-AC" china el-cheapo small converter, and delete the 60Hz fake seno output ("modified" square wave making parts), using only the DC-DC stage. These converters are sometimes very cheap and are easy to obtain in some places
I made the PSU for my car tube amp using one of these converters.