Author Topic: Something to do with cheap multimeters  (Read 2644 times)

0 Members and 1 Guest are viewing this topic.

Online NiHaoMike

  • Super Contributor
  • ***
  • Posts: 6111
  • Country: us
  • "Don't turn it on - Take it apart!"
    • Facebook Page
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline saturation

  • Super Contributor
  • ***
  • Posts: 4788
  • Country: us
  • Doveryai, no proveryai
    • NIST
Re: Something to do with cheap multimeters
« Reply #1 on: June 24, 2010, 10:12:18 pm »
Nice is it digital or analog?   ;D
Best Wishes,

 Saturation
 

Online NiHaoMike

  • Super Contributor
  • ***
  • Posts: 6111
  • Country: us
  • "Don't turn it on - Take it apart!"
    • Facebook Page
Re: Something to do with cheap multimeters
« Reply #2 on: June 24, 2010, 11:19:01 pm »
The ones pictured are analog, but digital meters should work. Might need some low pass filtering. A "floating" power supply would be needed to power the meters, but I think they can share one if the negative inputs are connected together. A cheap CEN-TECH I have (now dedicated to monitoring bench power supply current, powered by a small AC adapter) uses only 0.8mA at 9v. The positive side floats about 3v above the negative input, remaining constant despite battery voltage changes, so it seems like there's a zener diode or something. That can probably be supplied using a resistor to 5v. The negative side varies, so it probably isn't too critical. A charge pump run from a PIC output should be able to run it.
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 

Offline Kiriakos-GR

  • Super Contributor
  • ***
  • !
  • Posts: 3525
  • Country: gr
  • User is banned.
    • Honda AX-1 rebuild
Re: Something to do with cheap multimeters
« Reply #3 on: June 24, 2010, 11:31:40 pm »
He needs another one meter , to use it as  " Alarm " function ...  ( continuity mode )   ;D  ;D  ;D
 

Offline saturation

  • Super Contributor
  • ***
  • Posts: 4788
  • Country: us
  • Doveryai, no proveryai
    • NIST
Re: Something to do with cheap multimeters
« Reply #4 on: June 25, 2010, 12:43:58 am »
Thanks NiHao, but what I meant is the actual clock operation is done by a PIC 16F628A which outputs a proportionate current to read as hour, min and seconds.  So its a DAC output being read by real analog gauges.  So is it analog, or digital?  ;D






The ones pictured are analog, but digital meters should work. Might need some low pass filtering. A "floating" power supply would be needed to power the meters, but I think they can share one if the negative inputs are connected together. A cheap CEN-TECH I have (now dedicated to monitoring bench power supply current, powered by a small AC adapter) uses only 0.8mA at 9v. The positive side floats about 3v above the negative input, remaining constant despite battery voltage changes, so it seems like there's a zener diode or something. That can probably be supplied using a resistor to 5v. The negative side varies, so it probably isn't too critical. A charge pump run from a PIC output should be able to run it.
Best Wishes,

 Saturation
 

Online NiHaoMike

  • Super Contributor
  • ***
  • Posts: 6111
  • Country: us
  • "Don't turn it on - Take it apart!"
    • Facebook Page
Re: Something to do with cheap multimeters
« Reply #5 on: June 25, 2010, 01:53:06 am »
I would say it's analog, just like the "analog" gauges in modern cars that are actually connected to digital logic. The interesting part is that even before the days of digital logic, tachometers actually had primitive monostable multivibratiors inside! http://techno-fandom.org/~hobbit/cars/tachack/

Where the line blurs is if you had a row of LEDs arranged in an arc to emulate an analog meter. Like my idea for an add-on tachometer for the Prius (and maybe other hybrid vehicles as well) where there is an arc of LEDs for RPMs that light up blue when the engine is actually running ("squirt") and green when the engine is merely spinning ("warp stealth" or "B mode"). Other useful gauges such as battery current can also be integrated as additional LED arcs or other displays on the same board.
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf