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I learned a trick from w2aew: how to measure current if you don't have a current probe. He's using a N-channel JFET as example. I adapted it to a P-channel type - the J176. This second post is the practical part. No talk and simulation. A real circuit real measurements. Read Measure JFET drain current with a current mirror for schematics and approach.   Building the Circuit  This is extremely easy. Only four components are needed. The  NPN transistors in the current mirro ...
I learned a trick from w2aew: how to measure current if you don't have a current probe. He's using a N-channel JFET as example. I adapted it to a P-channel type - the J176. w2aew describes this in a video. He also published the notes. Follow and understand that first, because I will focus on translating this to a P-channel circuit.     Current mirror  This is a nice trick to measure the current in a component if you don't have a sensitive current probe. It's not perfect, but ...
I haven't thrown it away. I still have the Playstation 4, if you remember the last time we looked at How not to repair a Playstation 4 - The Risks of Second Hand Electronics , my intention was to look again at the vias and pathways on the board and see if I could resolder the connections from the HDMI port to where they were supposed to go.   However, unlike many of you who are very capable at soldering (according to What (metric) size have you managed to hand-solder ? ) I am... not, well ...
I reviewed an analog small signal switch in post 1: Simple analog JFET switch - part 1: schema, simulate and test. Here I'm checking what the limits are - the small linear part of the operational region where the P-channel JFET acts as a resistor. The circuit is published on neatcircuits.com   JFETs are linear for small signals. The schema here is for a consumer audio signal level, and that signal fits in that range for the J176 that I'm using. source: wikipedia   source: w2 ...
A simple low signal / audio "soft" switch with a p-channel JFET. It's very easy to make, with common components. Low power. The circuit is published on neatcircuits.com   I've ordered a set of transistors to play with. One of them is a ON Semiconductor (Fairchild) J176. This is a small signal P-channel JFET, designed for analog switching.   Let's first look at the circuit in the DC domain, with the switch open. Both drain and source are kept to ground by the 330K resistorsat in ...

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