astable

Hi

I wanted a circuit with a timer controlling an output preamp relay. A LED should blinking meanwhile and stay ON when the relay
get closed.*
I designed this with RL3 reseting U4. Q41 also starts RL2 the output relay.
It works but , sometimes, after a while, D7 restart blinking. Maybe there is not enough current for 2 relays.
How can I fix this ?
Mainly, is there a more clever way to achieve the goal ?
 

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rayma

Member
2011-04-29 8:37 pm
I wanted a circuit with a timer controlling an output preamp relay. A LED should blinking meanwhile
and stay ON when the relay get closed. is there a more clever way to achieve the goal ?

I designed an output muting circuit with a bicolor led, red when muted and green when enabled.
It's just a DPDT relay, LM555, a 2N2222, the led, and a few passive parts. If you're interested,
I'll get the schematic to you. (No Arduino required.)
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
Quick thoughts on your original circuit in post #1

If the collectors fall to near zero when on, then there is no problem with being able to drive two relays.

Cap on pin 5 is way to big. Typically its around 0.1uf

Pin 4 shouldn't be able to float, its needs a pull up to + supply of say 3k3.

If using an original type 555 chip then a 100uf cap should be across pins 8 and 1.