I'm needing to design a power supply for a receiver that requires +250V at about 116mA (can verify once I get home from work) and +12.6Vdc at 1A. I already got the necessary parts for the 12.6V regulator.
The question I have is will a 12.6Vac secondary work for the regulator circuit and give enough voltage headroom for it to regulate properly or do I need a higher voltage?
Also I want a choke input filter for the receiver supply as it will ensure the B+ is very low ripple.
What choke value should I use and what secondary voltage will I need for using solid state diodes?
I'm looking at either of these two transformers.
https://www.antekinc.com/as-1t275-100va-275v-transformer/
https://www.antekinc.com/as-1t300-100va-300v-transformer/
Unless there's a better transformer.
I would not be opposed to using two transformers either.
Might check what I have in my junk box before buying a transformer.
The question I have is will a 12.6Vac secondary work for the regulator circuit and give enough voltage headroom for it to regulate properly or do I need a higher voltage?
Also I want a choke input filter for the receiver supply as it will ensure the B+ is very low ripple.
What choke value should I use and what secondary voltage will I need for using solid state diodes?
I'm looking at either of these two transformers.
https://www.antekinc.com/as-1t275-100va-275v-transformer/
https://www.antekinc.com/as-1t300-100va-300v-transformer/
Unless there's a better transformer.
I would not be opposed to using two transformers either.
Might check what I have in my junk box before buying a transformer.
If you connect the two 6.3V secondaries in series and use a bridge rectifier, that
should give you about 16V DC, so you have 3.4V of headroom over 12.6V. Should be fine.
should give you about 16V DC, so you have 3.4V of headroom over 12.6V. Should be fine.
Yes, however will I still have that voltage when loaded with 1A?
The current supply is a 10V 1A transformer in series with the 5 volt winding of the power transformer that powers everything.
Concerning the amp power supply here's the numbers.
With receiver plugged in.
B+ 315.4Vdc
Screen B+ 259Vdc
Cathode voltage 9.56Vdc
Cathode current 63.7mA.
With receiver unplugged.
B+ 339.5Vdc
Screen B+ 339.5Vdc
Cathode voltage 10.42Vdc
Cathode current 69.47mA
Are those voltages ok for the 6BQ5?
I am planning on switching to fixed bias as well.
Will use the 10V 1A transformer for that and adjust the bias voltage until I get the same cathode current as I do with cathode bias. I may or may not use a mA meter to monitor the current, but if I don't use a meter, I might install a 1 ohm resistor between the cathodes and ground so I can measure the bias current using a voltmeter.
The current supply is a 10V 1A transformer in series with the 5 volt winding of the power transformer that powers everything.
Concerning the amp power supply here's the numbers.
With receiver plugged in.
B+ 315.4Vdc
Screen B+ 259Vdc
Cathode voltage 9.56Vdc
Cathode current 63.7mA.
With receiver unplugged.
B+ 339.5Vdc
Screen B+ 339.5Vdc
Cathode voltage 10.42Vdc
Cathode current 69.47mA
Are those voltages ok for the 6BQ5?
I am planning on switching to fixed bias as well.
Will use the 10V 1A transformer for that and adjust the bias voltage until I get the same cathode current as I do with cathode bias. I may or may not use a mA meter to monitor the current, but if I don't use a meter, I might install a 1 ohm resistor between the cathodes and ground so I can measure the bias current using a voltmeter.
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Power supply simulator shows 10.5 volts at 1 amp draw using 12 volt AC. I would use at least an 18 volt transformer.
Definitely.
I figured I'd need a higher voltage, bur had to be sure.
For the receiver B+ maybe I can get two 120/240 to 18V 1.5A transformers and run them back to back with the second transformer using the 240 volt tap of the winding.
Unless it's cheaper to get a 120-240 step up transformer.
I figured I'd need a higher voltage, bur had to be sure.
For the receiver B+ maybe I can get two 120/240 to 18V 1.5A transformers and run them back to back with the second transformer using the 240 volt tap of the winding.
Unless it's cheaper to get a 120-240 step up transformer.
You could get an R core trafo wired to your exact specs over on Ali. 18v winding gives plenty of overhead for the regulator...guess you'd want to double your requirement to allow for rectifier loss
Perhaps.
I know AnTek will have a low voltage transformer I need and maybe two of those would do what I need with the other one wired so the primary is now the secondary.
I know AnTek will have a low voltage transformer I need and maybe two of those would do what I need with the other one wired so the primary is now the secondary.
Why use 2 trafo when one could do? Eh, maybe you got a big chassis with lotsa room. Just keep in mind, the regulator will eat a couple volts. You can do a linear rectified DC supply starting with 12.6v but if you want regulated you'll need more volts than the Antek can supply...
I can get two for $26 each.
https://www.antekinc.com/as-1218-100va-18v-transformer/
However I will see if I can find a single transformer that will work.
Here's a 117V to 18V 2A transformer for $18.00
https://www.surplussales.com/item/_tp/16-0033.html
https://www.antekinc.com/as-1218-100va-18v-transformer/
However I will see if I can find a single transformer that will work.
Here's a 117V to 18V 2A transformer for $18.00
https://www.surplussales.com/item/_tp/16-0033.html
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So whatever else I find has to not put me over $54.00 or the two AnTek will be cheaper.
EDIT:
Things just got much cheaper.
Had forgotten I had a 115V primary to 215V 269mA and 6.3V 4A transformer. That said running it on 120Vac gives me a secondary voltage of 261.7Vdc.
I can likely use a CLC filter and if B+ needs to be dropped a good bit I can try the 6.3Vac winding in series with the primary.
That would work for the receiver B+ and the other transformer will work for the +12.6V tube heater voltage.
But if I do use that, I need to find a 120V to 50V transformer to take its place as I'm feeding 120Vac into the 215V winding so that I can get a 50Vrms supply to provide 60 something Vdc for a LED light with 100mA constant current regulator.
EDIT:
Closest I could find.
https://www.surplussales.com/item/_tp/82z2hv.html
EDIT:
Things just got much cheaper.
Had forgotten I had a 115V primary to 215V 269mA and 6.3V 4A transformer. That said running it on 120Vac gives me a secondary voltage of 261.7Vdc.
I can likely use a CLC filter and if B+ needs to be dropped a good bit I can try the 6.3Vac winding in series with the primary.
That would work for the receiver B+ and the other transformer will work for the +12.6V tube heater voltage.
But if I do use that, I need to find a 120V to 50V transformer to take its place as I'm feeding 120Vac into the 215V winding so that I can get a 50Vrms supply to provide 60 something Vdc for a LED light with 100mA constant current regulator.
EDIT:
Closest I could find.
https://www.surplussales.com/item/_tp/82z2hv.html
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I've got a toroidal transformer with two 15V secondaries at 95VA total.
I'll use that for the tube heaters.
I've got an older power transformer that has a HV winding and maybe just a 6.3V winding.
I'll measure the HV and see if it's usable. If the HV is too high I'll try it with the 6.3V secondary in series with the primary and see if the voltage is low enough.
If so I'll be well on my way to making the receiver supply separate from the amp.
All I'll then need are the components for the power supply.
For the 12.6V heater supply I'll use the existing regulator and new diodes and maybe a 10,000uF filter cap after the rectifier. I'll use whatever small value cap is recommended on the output of the regulator.
I'll use that for the tube heaters.
I've got an older power transformer that has a HV winding and maybe just a 6.3V winding.
I'll measure the HV and see if it's usable. If the HV is too high I'll try it with the 6.3V secondary in series with the primary and see if the voltage is low enough.
If so I'll be well on my way to making the receiver supply separate from the amp.
All I'll then need are the components for the power supply.
For the 12.6V heater supply I'll use the existing regulator and new diodes and maybe a 10,000uF filter cap after the rectifier. I'll use whatever small value cap is recommended on the output of the regulator.
I found a Halldorson power transformer that measures 238-0-238Vrms for a 121Vrms input.
That should work fine for the receiver.
I'd like to keep the receiver B+ at 250Vdc which was its original B+ voltage, however it currently runs about 270Vdc and works just fine so as long as the voltage is between 250-275Vdc I should be good.
I'll use two diodes and a large filter cap perhaps 100uF to filter the B+ for the receiver.
Depending on what the B+ is I'll either use a
C-R-C filter
C-L-C filter
Or just the capacitor
That should work fine for the receiver.
I'd like to keep the receiver B+ at 250Vdc which was its original B+ voltage, however it currently runs about 270Vdc and works just fine so as long as the voltage is between 250-275Vdc I should be good.
I'll use two diodes and a large filter cap perhaps 100uF to filter the B+ for the receiver.
Depending on what the B+ is I'll either use a
C-R-C filter
C-L-C filter
Or just the capacitor
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I need to look and see if I have a small chassis for the power transformer to mount on. I had thought about using a relay in the amp and receiver B+ supply controlled by the 12 volt heater supply, but it would be easier to just use a smart power strip and have the heater supply be what controls the strip.
For the power transformer, I can put the low voltage secondary in series with the primary to lower the B+ for the receiver.
For the power transformer, I can put the low voltage secondary in series with the primary to lower the B+ for the receiver.