Transistors: Vce Breakdown

RE: Transistors: Vce Breakdown

mcb1 — Tue, 31 Jan 2017 12:26:42 GMT

Interesting observations.

I was trying to find a paper that one of the relay manufacturers put out.

Adding a diode across the solenoid does indeed remove the voltage but it also slows down the release time of the relay.\

This may casue arcing of the contact due to the slow release, and is not the recommended method the employ.

I need to find it again.

Mark

RE: Transistors: Vce Breakdown

jw0752 — Thu, 26 Jan 2017 06:39:38 GMT

Hi Jon,

If you are not teaching why am I learning? You are doing a great job and your experiments are really appreciated.

John

RE: Transistors: Vce Breakdown

dougw — Wed, 25 Jan 2017 23:45:28 GMT

Well done - it was very interesting to see the unprotected transistor response.

RE: Transistors: Vce Breakdown

D_Hersey — Wed, 25 Jan 2017 20:16:38 GMT

You are showing what are called 'hard clamps.' For certain really big solenoid valves and stepper motors with mechanically reactive loads we need a 'soft clamp.' One of these types uses your clamp diode but inserts a Zener in series with it, pointing the opposite way

RE: Transistors: Vce Breakdown

rachaelp — Wed, 25 Jan 2017 18:30:54 GMT

Another great blog topic, nice work Jon! In previous blogs you've also done some circuit simulation to compare with your measurements. I was wondering if you simulated your various scenarios how close it would be to what you measured, especially in the case of no protection for the transistor and it going into oscillation.