Clicking follows notes

Moderators: George Geddes, David Martin, dave robinson, Iain Purdon, ecca

Re: Clicking follows notes

Postby scmitche » Fri Jun 27, 2014 10:21 am

Hi David,
Glad everything is working now.

Piet needed a 12V supply to allow use of a 9V regulator to ensure a well regulated, lower noise supply. However, with the spread in regulated voltage of the 7809 series it can give rise to potential problems with the NE55** series op-amps, which require a minimum of +/- 4.5V to meet the datasheet specification. The 7809 regulators can give as little as 8.8V output hence forcing the NE55** series op-amplifiers to run in an out of specification regime. To get around this I've started using TLC2272 op-amplifiers, which will work successfully at +/-2.5V and are still very low noise plus the output will swing almost rail to rail preventing any clipping-distortion issues. Being CMOS parts these op-amplifiers would also clip "gracefully" if they were overdriven slightly, which is not really an issue here but maybe useful knowledge for anyone using them as replacements in other pedal effects.

As I stated in my previous reply a good switchmode power supply rejects 50/60Hz much better than the 12V DC linear supplies, such as those used for NETGEAR modems etc., and has reduced mains supply hum in my own unit to zero.

Cheers,
Steve Mitchell
scmitche
 
Posts: 47
Joined: Tue Feb 26, 2013 11:03 pm
Location: Keighley, West Yorkshire
Full Real Name: Steve Mitchell

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