Hi there,
I'm building a fairly simple switch box using some relays, but I've come across some trouble trying to filter out DC hum (the box is switching audio signals for guitar pedals, basically a whole bunch of ins/outs).
I've been trying to figure out what value capacitor/resistor would be necessary to create a low pass filter and kill the 50Hz hum. I'm working with the equation F=1/2piRC which I believe is correct for figuring this out.
My problem is that the total load on the power circuit will vary depending on how many relays are active, which as I understand (and I could be way off) would require the C value in the formula to vary as well.
Numbers are as follows: Freq. = 50Hz, voltage is 9VDC, total potential load is close to 4Kohm (each relay is 275ohm when on, plus wiring, switches etc). Ground loops aren't testable yet as I'm still designing the PCB trying to accomodate a filter, etc.
Any help here would be much appreciated, if I've asked an old question just point me in the right direction.
Thanks!
I'm building a fairly simple switch box using some relays, but I've come across some trouble trying to filter out DC hum (the box is switching audio signals for guitar pedals, basically a whole bunch of ins/outs).
I've been trying to figure out what value capacitor/resistor would be necessary to create a low pass filter and kill the 50Hz hum. I'm working with the equation F=1/2piRC which I believe is correct for figuring this out.
My problem is that the total load on the power circuit will vary depending on how many relays are active, which as I understand (and I could be way off) would require the C value in the formula to vary as well.
Numbers are as follows: Freq. = 50Hz, voltage is 9VDC, total potential load is close to 4Kohm (each relay is 275ohm when on, plus wiring, switches etc). Ground loops aren't testable yet as I'm still designing the PCB trying to accomodate a filter, etc.
Any help here would be much appreciated, if I've asked an old question just point me in the right direction.
Thanks!