I have a 555 timer set up in monostable mode (9 seconds) triggered by a magnetic reed switch connected to pin 2 and grnd to control a relay and light. The output from the chip (pin 3) drives a TIP3055 NPN Darlington pair for current carrying purposes. It is run off of a 20amp 14v power supply and uses a 12v regulator chip. Pin 4 is set high and pin 5 is floating. The timer works great, but when another device connected to the power supply switches on, the 555 circuit resets and pin 3 goes low. The circuit voltage never drops below 12V. I think it is seeing it as a pulse to reset somehow. Any ides on how to correct this? I have read that the power side and ground should be tied together by a decoupling or bypass capacitor Could that be my issue? Thanks in advance
Dave
Dave
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