D
dave
Guest
I have a digital recoder similar to this.
http://www.alesis.com/protrack
It works fine on - batteries. Then I build my own -3V DC power unit
for it. It still works fine with that but there is hum *if I hold the
recorder while recordin*. If I don't actually touch the recorder the
hum is not there. I guess it's mains hum as there is no hum when run
on batteries..
The psu I built is spot-on the correct voltage and easily provides the
current demands of the recoder (500mA at most). The transformer I used
is screened and the screen to tied to ground. One side (+) of the DC
output is also grounded. It uses a LM337 regulator chip an has the
usual configuration. There is a 1u tant capacitor across the output
(as per design notes for this chip).
Any ideas how to cure(!) this hum problem appreciated.
http://www.alesis.com/protrack
It works fine on - batteries. Then I build my own -3V DC power unit
for it. It still works fine with that but there is hum *if I hold the
recorder while recordin*. If I don't actually touch the recorder the
hum is not there. I guess it's mains hum as there is no hum when run
on batteries..
The psu I built is spot-on the correct voltage and easily provides the
current demands of the recoder (500mA at most). The transformer I used
is screened and the screen to tied to ground. One side (+) of the DC
output is also grounded. It uses a LM337 regulator chip an has the
usual configuration. There is a 1u tant capacitor across the output
(as per design notes for this chip).
Any ideas how to cure(!) this hum problem appreciated.