Digital volt meter doesn't like a power supply?

[the13bats]

I have a 12 volt digital volt meter that plugs into a cars cigarette lighter,
On my hobby work bench it will work on for example the DC power supply I made from old Computer power supplies, but I have one older 3 amp 12volt power supply that will not light it up it will power about anything else except this digital volt meter why do you believe it will not power it?
Thanks,
Cheers,
Bats.

 

[AnalogKid]

Is it a linear or switching power supply?

ak

 

[the13bats]

Analogkid,
Thanks!
You got me there, I can tell you the power supply the digital volt meter works just fine on is the one I made from an old comp power supply but the old power supply that will not run it is a homemade thing I picked up at a garage sale.
I simply do not know what is linear or switching so perhaps clue me in....

 

[Alec_t]

How do you know the 'homemade thing' is working properly?

 

[AnalogKid]

In post #1 it powers "anything else".

ak

 

[the13bats]

How do you know the 'homemade thing' is working properly?

The so called home made one will power anything else I try on it, LED's , auto bulbs, etc including my radio shack lcd melti meter, or a needle style volt meter what it will not power/work is the cig lighter digital volt meter which will work on any other power supply I have, last night I tested an auto battery terminal for the high end car stereo people that has a digital volt meter and it also would not work on that one old home made power supply, if you desire pictures please email me [email protected],
A buddy suggested that the old power supply might not be filtered and have ripples making the digital volt gauges not work, but that idea is beyond my skill level....thanks!

 

[12vdc]

Is it possible the supply that will not "light" the meter ia A/C output?

 

[Arouse1973]

Is it possible the supply that will not "light" the meter ia A/C output?

I think it's 12vdc 12vdc. Sorry couldn't resist that.
Adam

 

[the13bats]

I assure you it is 12VDC at least to the point that as I have said it it will power all my 12v dc stuff besides these digital volt gauges,
I will be honest I feel better that you guys way more savvy on all this than I am don't know why it's doing this.

 

[Colin Mitchell]

All your "DC stuff" may have its own internal rectifier and regulator.

 

[the13bats]

All your "DC stuff" may have its own internal rectifier and regulator.

So can I upgrade this old power supply to have what it needs to run the digital volt gauge?
Even the little black block pull in the wall units will run that cig lighter volt meter.
See the thing is this old supply is pretty nice otherwise two 12v outputs that are variable voltage from 0 to 12 fused and relay protected however it needs a voltage display to know what output voltage it's putting out and the cig lighter one would work out nicely.

 

[Colin Mitchell]

Put 1,000u 25v across the output and see if the voltage can be read.

 

[the13bats]

okay here is where I show my novice level, what is that thing you recommend?
When I go to skycraft what do I ask for or look for?
Thanks.

 

[the13bats]

Colin,
Thanks you fixed it for me,
I looked up the part you listed learning it was a capacitor,
So I looked at my parts pile and found one on a board 1000uf 16v
I placed it between the hot and ground outputs on the power supply and then hooked up my radio shack multimeter, and started turning the power knob up and see the voltage going up and up and up,
Before I added the capacitor it maxed at just over 12v now it will go over 19v!
I then tried the cig lighter volt meter that would not work, it now works!!!!
It will read the same as the radio shack meter up past 19V however the cig lighter meter needs to be powered to work so it dies down about 4v, which now explains to me why some of the ebay generic digital volt meters have 3 wires as they need to be powered to display.

 

[Colin Mitchell]

See, how clever you are.