Annoyingly simple 555 problem
Annoyingly simple 555 problem
(OP)
Iv'e spent ages trying to solve what should be a ridiculously easy problem but it's got me stumped.
A standard 555 monostable circuit, output drives a small relay that controls a small motor - it should turn on for 2.5 seconds when the 555 is triggered but just turns back off again - 555 doesn't seem to latch high. Without the motor all is fine so I assume it must be drops on the power supplies turning the 555 off?. Tried putting capacitors across the power supply and the motor but no good. One solution is to separate the motor and 555 power supplies but would rather avoid this.
What am I missing?
Thanks for any help.
TopRigger
A standard 555 monostable circuit, output drives a small relay that controls a small motor - it should turn on for 2.5 seconds when the 555 is triggered but just turns back off again - 555 doesn't seem to latch high. Without the motor all is fine so I assume it must be drops on the power supplies turning the 555 off?. Tried putting capacitors across the power supply and the motor but no good. One solution is to separate the motor and 555 power supplies but would rather avoid this.
What am I missing?
Thanks for any help.
TopRigger
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RE: Annoyingly simple 555 problem
RE: Annoyingly simple 555 problem
RE: Annoyingly simple 555 problem
RE: Annoyingly simple 555 problem
RE: Annoyingly simple 555 problem
RE: Annoyingly simple 555 problem
Is the motor using the same 12 V supply? How low does
it drop when the motor starts ?
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RE: Annoyingly simple 555 problem
RE: Annoyingly simple 555 problem
A combination of the diode (thanks BMNET) and experimenting with various capacitors across the motor terminals fixed the problem - I suspect a particualrly noisy motor.
Thanks to all who answered.