555 power supply, voltage regulator

[StoopKid]

http://www.ledsales.com.au/kits/nixie_supply.pdf
With this 555 power supply, is it ok to use a 9-12V wall adapter
directly into the circuit, or would a voltage regulator first be
ideal? I figure it IS a voltage regulator so thats not necessary but
then again for all I know it would be better to use one.

Thanks

[Quixotic Nixotic]

I have never had a problem with the 555 circuit using a wall wart
without a voltage regulator on the power input.

I have had a problem with the MAX1771 circuit with a couple of rogue
unregulated 12v supplies that give out much higher voltages than 12v
without a load and which pop the MAX 1771 as soon as they are plugged
in.

John S

[Adam Jacobs]

Check the voltage output of your wall-wart with a voltmeter when the
supply is unloaded. If the voltage is below the maximum allowed voltage
in the IC's datasheet, then you're fine. If not, then get a new
wall-wart. :) The short answer is that: No, it doesn't make sense to
send the input to your HV supply through an additional voltage
regulator. Modern CMOS parts have a very wide range of acceptable supply
voltages, I normally use a small (100ma) 12v linear supply wall wart..
It swings as high as 16v unloaded. The MC34063's I use handle 16v just
fine. The only conditioning that I do to the suppply prior to the HV
switcher is to send it through a 1N4007 (to protect my circuit in case I
accidentally plug in an AC supply or a reverse polarity supply.. It's
happened!) and a bypass cap or two.

-Adam