https://headwizememorial.wordpress....e-ended-otl-amplifier-for-dynamic-headphones/ I'm interested in building this amplifier, but I'm unsure of the power supply circuit. The transformers are quite expensive and aren't readily available in europe. Is there an alternative power supply I could use? Is any 150vdc power supply suitable
You can use this for B+, they will have similar one for filament.
https://www.mouser.ch/ProductDetail/Triad-Magnetics/VPT230-220?qs=wkKrz7WmEgMVJQHjyRuIng==
If you buy both at mouser (or Digikey) you will spend around Eur 70 (incl. Shipping)
Erik
https://www.mouser.ch/ProductDetail/Triad-Magnetics/VPT230-220?qs=wkKrz7WmEgMVJQHjyRuIng==
If you buy both at mouser (or Digikey) you will spend around Eur 70 (incl. Shipping)
Erik
Early tube radios ran on three batteries. To avoid confusion, they were named A B and C on the connections.
A - Filaments 1.5V or 2V (heaters)
B - Plates 45V 90V 135V
C - Grid bias 7.5V
We have gotten out of the habit of using grid bias. (later tubes use much smaller grid bias and we can usually provide bias within the circuit.)
The Heater circuit for wall-power radios grew to be 6.3V and that's what we call it.
Somehow only "B" survived in regular use. Even if it is not a battery. It obviously has a + and a - but people tend to say "B+" anyway.
so do I completely replace the B+ circuit with the toroidal transformer you gave a link to? What about the 6.3vdc heater circuit
The transformer from the link I gave you is used for the 150vdc. You will need a 2nd transformer for the filaments. Otoh, that circuit for filament heaters is quite old fashioned, nowadays I would use a transformer with 7V secondary and a low dropout regulator (less heat), or go for a switched mode PS. (I think DC is good there, as this is a headphones amp)
https://www.mouser.fi/ProductDetail/Triad-Magnetics/VPT12-4170?qs=wkKrz7WmEgPxHMYAWLcN5A== would this be suitable for the 2nd transformer?
No, according to the schematic you will need 9V transformer, so this is good
https://www.mouser.ch/ProductDetail/Triad-Magnetics/VPT18-2780?qs=wkKrz7WmEgOsofzfskZP0w==
Use the two secondaries in parallel.
The schematic for the heater will produce a lot of heat, the author mentions 10W on the regulator, and also the bridge rectifier will produce some 4W of heat. So you will need a good heatsink for these, I think about 1C/W (that means it raises 1 degree centigrade per dissipated watt, so 14 degrees above room temperature in your case), somethink as this https://www.mouser.ch/ProductDetail/Wakefield-Vette/423A?qs=8GtUBYxqNFD3l2E/uJVq9A==
Personally I would probably do it different, but I do not know versed you are with electronics?
Erik
https://www.mouser.ch/ProductDetail/Triad-Magnetics/VPT18-2780?qs=wkKrz7WmEgOsofzfskZP0w==
Use the two secondaries in parallel.
The schematic for the heater will produce a lot of heat, the author mentions 10W on the regulator, and also the bridge rectifier will produce some 4W of heat. So you will need a good heatsink for these, I think about 1C/W (that means it raises 1 degree centigrade per dissipated watt, so 14 degrees above room temperature in your case), somethink as this https://www.mouser.ch/ProductDetail/Wakefield-Vette/423A?qs=8GtUBYxqNFD3l2E/uJVq9A==
Personally I would probably do it different, but I do not know versed you are with electronics?
Erik
https://www.audiophonics.fr/en/line...ly-module-dc-lt1084-49v-to-35v-5a-p-8425.html could I replace the heater circuit with this power supply?
That is a good find indeed, exactly what you need. Still, with the 9V AC Trafo you wil have a lot of heat on that heatsink, I am almost sure that 7V AC would be enough for a clean 6.3V out.
Left field question on power supplies please - I have almost free ( I only pay shipping) supply of excess LiPo4 batteries for off grid wind farm storage... So can I use a mother of a battery (120 to 150 volts and 100 Amp Hours) to power an OTL amplifier? It would be recharged from a wind turbine so very good environmentally! Thanks in advance.
I have built an iteration of this amp.
You can use a 150 VAC transformer for a simple, unregulated, filtered PSU.
I went ahead with tube rectification in my final build.
For the filaments, i suggest you go AC-lit.
Just use a center tap (artificial even) and elevate filament voltage 60-70 Volts above ground.
You can use a 150 VAC transformer for a simple, unregulated, filtered PSU.
I went ahead with tube rectification in my final build.
For the filaments, i suggest you go AC-lit.
Just use a center tap (artificial even) and elevate filament voltage 60-70 Volts above ground.