Electronics And Tech Help

[Winterkid]

I believe my Multimeter I just bought to be overestimating all the voltages I measure with it.... All batteries out of the packages read as 1.6-1.65 v, and the DC adapter I bought from Walmart on the 3V setting shows me 4.9-5.2VDC. The 9V adapter that came with my Atari 2600 Flashback 2 Retro System (Pretty kewl console toy, btw) reads at about 15V. Is there anyway to calibrate a Digital Multimeter to better accuracy? It only cost me $10, but still, I don't want to just throw it away.

 

[pcklee123]

I think your multimeter is correct. Batteries (non rechargeable) fresh out of the package are 1.6-1.7V
Unregulated DC adapters are usually at least 1.4 (square root 2) times higher than stated voltage when not connected to any device. When connected to a power hungry device, it should drop to the correct voltage.

 

[Winterkid]

Then I've been feeding my GP32 roughly 3v of power when the meter says it's reading 5v? There a way to verify this?

 

[calqlater]

You can put the volt meter inline with the GP2X while it's plugged in to the power source. You'll probably need to buy/make some connectors to do that in a non-frustrating way, however.

 

[Winterkid]

Actually, the connector is a multi-type connector, so I'd just have to connect the meter to one of the other plugs to measure...

 

[nubie]

Just buy a good Digital Multimeter, I got a Cen-Tech for $3 at Harbor Freight, it is as accurate as the multi-hundred dollar ones at my college automotive program.

The battery seems to be worthless, but a 9-volt from the Dollar Tree store should fix it.

Tip, trust digital multimeters, they don't lie. Don't trust wall warts, they lie.

 

[Winterkid]

So if you're right and the meter IS accurate, the voltage across the DC adapter's plug only drops down to 4.1 volts when it's connected to the GP2X. There anyone who knows for absolute certain if it could handle that? I know 3-3.3V is the desired, but it looks like this adapter wont get that low.