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djrix  
#1 Posted : Monday, January 2, 2017 10:15:18 PM(UTC)
djrix

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Czech Republic

Hi, i bought the pcb for JT and Volumite uP few months ago. Now i have builded the i2c controller on my own PCB with Attiny,MCP23008 and ULN for driving the relais.
Everything works fine, but in some cases i am able to "find" the position on potentiometer, where some relay starts to oscilate with high frequency. I tried to separate the supply voltage to the coils on JT from another PSU, which does not solve the problem. Is there any other thing to watch out ?

Thanks, Petr
djrix  
#2 Posted : Wednesday, January 4, 2017 6:15:45 PM(UTC)
djrix

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Czech Republic

OK, small progress. As i had not the vreg for 5V on board near attiny it looked that was the point, why the relais starts to oscillate, the uP is really sensitive to the 5V PSU stability. Now i have 7805 on pcb near Attiny. Nevertheless, when i tested the circuit with multi turn trim there is still one point where the relais started to oscilate. Vcc is 5,028V and at 2,1238V on trim wiper thats the point where last two relais oscilating like a motorboat :D
Brian Donegan  
#3 Posted : Friday, January 6, 2017 2:18:37 PM(UTC)
Brian Donegan

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This is usually a sign of not enough driving current, which is affecting readings of the ADC in the uC.
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