replacing SDPT with transistor

[tolerant]

Hi all, can you please advise me on how to use transistor/s to replace the nosiey relay. Here is the schematic of what I'm trying to do ...... thank you

Title should read Replacing SPDT Relay with transistor/s ....... I should proof read before submitting

 

[BeerBelly]

I don't see any filtering on the power lines or a spike diode on the relay. It's no wonder you have a noise problem and maybe a spiked out IC.

 

[alec_t]

Here's how you could make a SPDT equivalent:

The 'In' would come from pin 3 of the first 555. Out1 and Out2 would provide the V+ voltage for the other 555s.

 

[BeerBelly]

By the way, Welcome to the forum.

 

[KeepItSimpleStupid]

Why not use an OPTOMOS relay?