Hi All
I've just acquired a universal AC/DC adapter that plugs into the wall and outputs 3, 4.5, 6, 7.5, 9 and 12V at 500mA. Can I use this directly into a simple circuit like a 40106 oscillator (from Nicolas Collins' book)? I have the oscillator breadboarded, going into a 1W simple amp (little kit I bought) and then going into a mixer and finally into a big Yamaha HiFi amp. I've been using a 9V battery and it sounds great. Will the adapter work as well? I've seen videos and web pages describing another small circuit that needs to be used between the adapter and the circuit:
http://www.solorb.com/elect/musiccirc/9vbatelim/
I don't think this applies as I can choose the voltage on the adapter. Also my understanding of Amperes is a bit loose but I think that 500mA is it's capacity as opposed to it's output so as long as my circuit doesn't exceed 500mA I'm ok. Is this right? Will my circuit be likely to exceed that limit?
Thanks
Scott

 

I would say yes. If it is the unit I'm thinking about it doesn't regulate though, so plan on using regulators in your circuits. It isn't a big deal, they are cheap and plentiful.

 

The 7809 voltage regulator IC needs to have an input voltage of at least 11VDC.
Your adapter does not have its voltage regulated so its voltages will probably be very high with a load that is much less than 500mA. The 12V output might be 18V and the 9V output might be 13V.

 

Something else, in a lot of circuits it doesn't matter if it regulated or not, so this could be useful in either case.

 

Thanks guys. I just checked it with a multimeter and when the dial was on 4.5V the output was 7.8V and when it was on 6V the output was 10V. Should I go by what the meter is telling me or by what the adapter is telling me? Also, if I go by the multimeter is it best to use 7.8V or 10V on a circuit that runs on a 9V? or does it not matter?