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Hum with relay switch

PostPosted: 08 Jun 2014, 20:36
by Mbas974
Hi, I build a pedal 9V power supply
using a internal PCB trasf. having 15V out stabilized with diodes caps and regulated with 7809 etc... (standard stuff... ... rps_sc.pdf)

It work ok (silent) with 3PDT switch but as I use it with relay switch pedal
it is really noisy..lot of hum.. is it a frequency problem or what ???