The high di/dt of MOSFETs would make it worseseyyah said:Is using mosfet better tan bjt?
Forget about scheme #2... you dont want such a high current flowing through the capacitor when transistor turns on.seyyah said:Which configuration can help me more?
Regnum said:I'd like to know how you do perceive the problem...
Some logic circuitry crashes as operating relays, or transistors break?
In schemes 1, 2 and 4, see that you're clamping the collector to [Vcc + Vz] volts, so It could be breaking the transistors. (What's the sense of those zener diodes...?)
Regarding scheme #3, it may be OK but it's more orthodox using the scheme #1 of my drawings
-Always use bypass capacitors from the VCC terminal of relay to the transistor emitter.
It is difficult to use L for now. Because I'm trying to solve the problem of a finished design. I'm rather restricted to make major changes. Using LC may be done in the rev2 after solving the problems of rev1. I'm using various capacitors for decoupling. Also logic and relay circuitry has different supplies but their ground is common.-Always use decoupling circuitry from Relays-VCC to Logic-VCC (LC-networks, and separated voltage regulators)
-Always use star schemes for GND and VCC routing (don't ever return the relays current trough the logic GND; do it directly to power supply GND point)
For example what? (and how?)rauol said:Use a transient voltage suppressor and MOV
...maybe you won't solve it till you improve the PCB :!:...logic and relay circuitry has different supplies but their ground is common...
...But after solving these problems, i will try to do a better pcb design...
Regnum said:Try this choice
good luck
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