My opto limiter project is doing fine - I'm on holidays for a week, so I can spend a lot of time soldering.
Electrolumiscence photo coupler finished.
CV path was planned to be like LA3A with step up transformer, but in the end im using a high supply voltage and a high voltage MOSFET (IRF820) instead of a tube in a LA2A-like circuit.
Audio amplifier is also finished. I had planned to copy the LA3A transistor amp; but now I bought some tubes and built a copy of the LA2A circuit. I just tested it - works great.
(As I hadn't intended to use tubes, my transformers weren't chosen for heater voltage range. So used the 26V supply that was intended to feed the transistor amp for a series connection tube heater circuit instead. A funny circuit, with a LM317-based 340mA source, and two TL431-based shunt regulators for 12.6V (12BH7 series connected) and 6.3V (ECC83 parallel connected). Not exactly straight forward solution, but it works, and I don't have to buy new power transformers. (;->)
All right, and here come the stupid questions:
What are the data for the input and output transformers of the LA2A?
I think I've read about the output transformer having a 4:1 ratio.
10k : 600R - is that right?
And the input transformer? 1:2 ? or 1:2 ??
The potentiometers for gain and compression, 100k,
Are these linear or log / audio taper types ?
JH.
Electrolumiscence photo coupler finished.
CV path was planned to be like LA3A with step up transformer, but in the end im using a high supply voltage and a high voltage MOSFET (IRF820) instead of a tube in a LA2A-like circuit.
Audio amplifier is also finished. I had planned to copy the LA3A transistor amp; but now I bought some tubes and built a copy of the LA2A circuit. I just tested it - works great.
(As I hadn't intended to use tubes, my transformers weren't chosen for heater voltage range. So used the 26V supply that was intended to feed the transistor amp for a series connection tube heater circuit instead. A funny circuit, with a LM317-based 340mA source, and two TL431-based shunt regulators for 12.6V (12BH7 series connected) and 6.3V (ECC83 parallel connected). Not exactly straight forward solution, but it works, and I don't have to buy new power transformers. (;->)
All right, and here come the stupid questions:
What are the data for the input and output transformers of the LA2A?
I think I've read about the output transformer having a 4:1 ratio.
10k : 600R - is that right?
And the input transformer? 1:2 ? or 1:2 ??
The potentiometers for gain and compression, 100k,
Are these linear or log / audio taper types ?
JH.