looking for 50+50VCT preamp transformer

Last edited:
For a 50VA there is always Hammond for people in the other side of the Atlantic.
It's hard to find ready made 100VACT in a smallish 15-30VA rating.
Thank you for the tip. Mouser at US carries the model you suggested.
166G100 Hammond Manufacturing | Mouser

Actually, Digi-Key in US also stock Harmond Transformers. The closest is a 36VA, 60V+60V. This one may work too. It is smaller, thus cheaper at Digi-Key.
164J120 Hammond Manufacturing | Transformers | DigiKey
 
Last edited:
Voltage multiplier circuit perhaps? Low power high voltage secondaries are less common.
This is actually the same question that I asked 2 years ago.
3 outputs PSU for power amplifier

I have a 640VA toroidal (Avel Lindberg from Parts Express) for the power amplifier output stage. It is 40V+40VAC and results in 56V+56VDC. The smaller 50V+50VAC will drive a PSU board to create a 60V+60VDC supply for the input and voltage amp stage.

The idea of using a voltage doubler comes across my mind. I understand the basic doubler circuit, but I lack the experience to select the proper components for good results.
 
It's easy, post your circuit here.

40V-to-80V-Voltage-Doubler-circuit.jpg

It goes to a +/-60VDC regulator. What should I add in detail?
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
240VAC does not make 80V DC. The number 1.4141 comes into it.

You seem to be thinking "doubler". This type doubler does not need all those diodes. As drawn you get 112VDC twice.

Work backward from output spec. 60V DC regulated wants 10%-40% extra to cover sag and losses. 66VDC to 84VDC. The AC is 0.707 of that, 47VAC to 60VAC. (Indeed VAC=VDC is safe bet for designing smaller regulator supplies.)

What is READILY available in that zone? First thought is 48VAC (or 24+24), a very popular chunk of iron. Two diodes and two caps make this into +/-71VDC. That leaves very little margin for line-sag and ripple. 25VAC (or 28+28) may be a safer bet.

An extreme DIY-only plan, for 120V land, is a 240V:120V transformer of good current rating (double the VA). Run the 240V winding on 120V. Low-low magnetic flux is good. The "120V" secondary is now 60VAC, making 84V raw DC, a bit high but may be tolerable for a 60V clean output.
 
Umm, I see a problem with the schematic you have drawn.
It is neither a bridge nor a doubler? Maybe it will result in magic smoke?

To be a 'doubler' you need to loose the connection between the transformer and the bottom 2 diodes (pin 4). The bottom pair of diodes are then redundant.

To be a 'bridge' you have to loose the connection between the transformer and the C1 / C2 junction. I know you know this...

I think your original ask for a 50-0-50 volt transformer (or close) is the better way to go here.
 

Attachments

  • 40V-to-80V-Voltage-Doubler-circuit-001.jpg
    40V-to-80V-Voltage-Doubler-circuit-001.jpg
    100.6 KB · Views: 35
Last edited: