Recent content by temol

That's correct. Here

I just uploaded the schematic to ltspice. RS = 12k and J201 with Vp -0.7V requires RD of 105k to get 4.5V on drain. With RS 1.2k RD is 20k (for the same transistor).

In the case of J201 and a 12k source resistor, a 50k trimmer may be too low. You could try 100k. The higher the RS value, the larger the RD value needed to get the same drain voltage. Maybe the original has a larger trimmer? Or maybe a different JFET? Or 1.2k instead of 12k?

In the vast majority of cases, the physical dimensions will be more important here, so that they fit the footprint on the finished board. Power rating would be important for example for the output transformer in an amplifier.

From what I remember they differ in maximum output power. TL - 75mW, TM - 200mW, TU - 460mW.

Bump...

I have a design for a similar box but I keep forgetting to make it :)

Cheaper, smaller, and adjustment is precise enough in most cases?

B - 0.58V, C - 0.8V

Here it is.. BC109C, BC211, MP38A. Voltage readings on a schematic below. And working pcb. The only thing I don't like about the sound is a bit fizzy decay of the notes. I don't know (yet) if that's a feature or something to manage that requires hammering here and there. The rest is pure...

What kind of devices do you plan to power with this power supply? What range of voltages and currents? A few mA? A few amps? 9V? 30V? Analog pedals don't draw much current, and it may turn out that at 9V and 10mA you don't need such gadgets at all.

That's some cool info, thx! Here, I have bc109c for Q1 and Q4, KSY 62B for Q2 and Q3. I don't have too many low hfe candidates stashed. I could not source any 2N3903 locally. In my collection I found other potential victims - BC211, BF258, BF257, KF507, 2N2193, BSX61, all large metal can, TO39...

Thanks! I found a few pieces with relatively low values - I chose 64 and 88. Works as it should :)

What is the preferred hfe range for q2 and q3? Below 100? Below 60?

Regarding Idss - I think we need to move the decimal point, assuming that the current is in mA. For 5457 the current is more likely 2.8mA and not 0.28mA