LED's for a voltmeter ?

[petemoore]

    ...since LED's are easy to find when salvaging...
   And DMM's aren't always attainable...
  A 'Mcguyver' LED meter ?
   With Global LED circuit use of current limiting resistors:
  A string of LED's, 1rst will light when it's foreward threshold is met.,,tells when the node is <the threshold voltage.
  2x LED's doubles that.
   The number of LED's to determine the threshold of 1/2v [ie build quick 1/2 resistive divider so a 'mark' of 1/2v [fresh battery] can be placed...ie 3LED's light with the 1/2v, 4 LED's don't.
  And of course the continuity tester: supply + LED [and CLresistor]...an open circuit which can be closed by touching probes together.
   Being able to get ballpark voltages is often enough for debugging, certainly continuity checker would help.
  Maybe a way for anyone salvaging a monitor to cobble something with enough ability to identify pass/fail of stages to get circuits off the ''needs DMM to do any debugging list'' ?

[amptramp]

You can make a LED voltmeter out of an LM3914.  If you drive strings of LED's from a voltage source, there is not much controlling the current through the LED's and you could burn out an entire string of them.  You need a resistor to the outside world either from each LED or in the probe.

http://www.national.com/mpf/LM/LM3914.html#Overview

http://www.datasheetcatalog.com/datasheets_pdf/L/M/3/9/LM3914.shtml

But be aware that some DMMs are now approaching LED ladder type voltmeters on price and have higher input impedance as well.  And a DMM has a resistance scale that will serve as a continuity meter.

[RedHouse]

...be aware that some DMMs are now approaching LED ladder type voltmeters on price...

Most definitely, you can hardly buy an LM3914, a piece of perf-board, plus shipping, for the $1.99 that gets you a china DMM from Harbor Freight when they're on sale.
(under $5 normal price)