Help with cleaning of AC please

[Graham]

Hi
The circuit on page 22 fig. 7 assumes that you feed it with a smoothed DC filtered supply. The circuit on page 26 fig.18 shows a negative output supply using a positive regulator but shows the correct components, i.e. a bridge rectifier, reservoir cap. and output decoupling cap for stability. The circuit on page 22 fig. 9 maybe the one that is confusing you. It's confusing me too! A 470 microfarad capacitor straight from the 120 volt AC mains onto the regulator. That really would reduce the ripple, ( when the breaker or fuse went BANG!).

[pedja089]

That isn't 120Vac, it is 120Hz... And that is test circuit for Ripple Rejection test.

[Graham]

Hi
Thank you for pointing out the error. Although in defense of my mistake, the circuit does come under the heading of "Typical Applications' and is scarce on detail. But..... it does read 120Hz which I miss-read as 120volts, the US domestic outlet voltage, nominally! Sorry.