9V - 300mA AC Adapter with Basic Stamp HomeWork Board

B_Gulliver

I purchased a 9V - 300 mA AC Adapter from RadioShack and I wanted to connect it to my Basic Stamp HomeWork Board where the 9V Battery connector is. Before doing this however, I plugged the AC Adapter into the wall and measured the voltage with a multi-meter. The reading I'm getting is 11.04 Volts. I'm wondering if this will work without damaging the Basic Stamp board. If not, then perhaps I should return this AC adapter and try to find one with a voltage closer to 9V.· I'm not sure what the tolerance is on the Basic Stamp for the Input Voltage.

Can anyone give me a suggestion or advice on this? Thanks!

dandreae

You purchased an unregulated supply, if you add a load you'll see that the voltage reading will drop down to·9v.

Dave

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Dave Andreae

Parallax Tech Support·

Mike Green

The 9V adapter is an unregulated power source. You're reading the voltage at "no load". If there's any significant power demand from the adapter, the voltage will drop much closer to 9V. The regulator on the HomeWork Board can handle much higher voltages without damage. The issue is mostly heat dissipation. Anything above 5V has to be discarded as heat. That's probably not a practical issue with the HomeWork board (because of the low power demand), certainly up to maybe 12 volts or so, but the general notion is to keep the input voltage just high enough to make the regulator happy. What you have will work, don't worry about it. If your voltage regulator (see the documentation for the HomeWork Board) gets really really hot or your circuits stop working after a few minutes, try a lower voltage power supply (as low as 6V). The Stamp itself and a couple of LEDs won't draw much current.

B_Gulliver

Thank you very much for the responses. Exactly the info I was looking for!