understanding new toy amp meter

Discussion in 'General Electronics Chat' started by madman6233, May 20, 2011.

  1. madman6233

    Thread Starter New Member

    Mar 4, 2011
    hello again I got a new toy. It has a voltage panel and an amp panel, both analogue, on it. Has 3 switches on the front and what appears to be an output under amps and volts. The back has several input points and 1-3 other inputs. I am going to take it apart and put pics up here in a little bit, but i know from the experiments sect that analogue displays are sensitive( i blew several trying to build a voltmeter) so i do not wish to do this again.
    I thought I would get advice on what to do and not to do to/with it.
    I am trying to build an inline meter out of it. Between homemade power supplies and tattoo machines. This should allow me to understand what changes i make to my coils affect the machines. I cannot post a schematic as i bought this surplus but will put up pics of the inside as well as the out. thanks
  2. madman6233

    Thread Starter New Member

    Mar 4, 2011
    couldnt figure out how to edit my post so i did it like this here are pics:
    I am not sure why it has a voltage in on the back but that is connected in series to every other input





    I am so confused.
    I wanted to test this out today but i have decided to wait until i know i am not going to break it thank you guys for all of your help.
  3. Kingsparks


    May 17, 2011

    From the pictures it looks like you have a volt/ammeter. Input a voltage from a power supply and output some other project. That's about all I can tell you from the pictures. Never seen one like that but it is not a stand alone item, meant to be used with other equipment I would guess. And that's all it is, a guess.

    I doubt it has any control function, only monitoring and the various output jacks and pots on the back are for different outputs, more then likely low current with some adjustment by the pots back there. The switches on front look to be selectors to set the ranges of the voltage and current MEASUREMENTS, not the value.

    What are you going to use it for, making a meter I think your post said to measure, what, voltage between your power supply and tattoo machine.

    You might consider a couple inexpensive multimeter's like you can get from many different sources for around three of four bucks. I have about a dozen I keep just to use as panel meters.

    Bout all I can say. :cool:
  4. someonesdad

    Senior Member

    Jul 7, 2009
    I hope you didn't pay more than about a dollar for that, as it's old, homemade, and a bit corroded. You can buy digital multimeters from e.g. Harbor Freight for a few bucks and they can sometimes substitute nicely for meters. You should have one or two, as they are much more versatile than analog meters (but analog meters are still nice for some applications).

    If you've been blowing meters up, you should probably go read the ebook section on DC metering circuits. Analog meters are often 50 μA current meters, so you have to know how to add resistors to the circuit to allow them to measure the voltage or current range you want to measure. The principles are quite simple, so take a look at the ebook.
  5. madman6233

    Thread Starter New Member

    Mar 4, 2011
    thank you very much and I have several digital meters yes but have had issues learning to figure the amperage but I was guided to buy several small resistors to place across the device and do the math to figure the voltage drop and therefor know the drawn amps.
    but the people i am selling these power supplies to wouldn't have a clue what i was talking about so I decided to go for a nice and simple display that tells them everything. With this I am hoping to be able to easily explain the difference between their supplies ran with a lm317 and mine.
    I still don't quite understand why the difference is so great between a switch supply and non but the performance shows it all and when it was suggested i move from a 17v transformer to greater than double my requirement the temp difference became noticeably cooler so I accept it as fact and I am truly trying to understand the ebooks but alot of it baffles me still but i am hooked on this site and love the experiments so I also got a new soldering station today I am hoping to really improve those skills as well soon
    Thanks again I am going to make an io box tomorrow to hook up the phone jacks i use to this device instead of permanently altering it and i think it was 5 dollars which seemed worth it since the displays are much more than that locally