Didn’t take as long as I thought to build the new anode current sensor for the valve curve tracer. A simple PCB was used to solder directly the components for a quick solution. Here is how it looks:
I tested this new circuit with some valves from high transconductance to low current ones. The current amplifier works like a charm. I used a CCS first to calibrate the x10 output and found a great linearity from 1mA up to 100mA. Currently I used my bench power supply to test this but I’m planning to do some major surgery to the tracer and include this sensor inside the main chassis.
With a dual 15V supply the AD8479 can work with up to 600V in common mode. This is perfect for my tracer and can be used to sense anode and screen currents.
Tracing a 49 NOS valve
The proof is in the pudding!
Wired anode current sensor
Curve tracer and new anode current sensor
