[Test-Equipment] Question Regarding Fluke 8050A

[Barry]

I was using a transistor but then that inverted the signal and I had to add another one to invert that (maybe I was doing something wrong?)

When I was thinking of powering this all from a +5 supply, a couple of resistors between +5 and -5 and a transistor was working fine but when I changed that to run strictly off the -5V supply, it got a bit messy so I thought a single chip would be a more elegant solution.

Are the LS and/or CH devices lower power?

Thanks so much,
Barry - N4BUQ

----- Original Message -----
> From: "KA4INM" <ka4inm at gmail.com>
> To: "Discussion of Electronic Test Equipment" <test-equipment at mailman.qth.net>
> Sent: Thursday, June 4, 2015 9:08:51 PM
> Subject: Re: [Test-Equipment] Question Regarding Fluke 8050A
> 
> On 06/04/2015 09:33 PM, Barry - N4BUQ:
> 
> > Yes, that would be my preference as well.
> 
> > As an update, I connected all five displays on a breadboard, powered it
> > with an external supply, and watched the current demand.  The maximum I
> > could get out of all those was about 310 mA.  I tested them with the four
> > primary digits connected together and stepped it through 0000, 1111, 2222,
> > etc. (the first digit the +/-/1 and it doesn't pull much current).  Oddly,
> > 4444 drew the most power.
> 
> > It turns out I had an SN7400N that I was using as an inverter and I was
> > testing with that out of the circuit.  When I plugged that in, though, the
> > current demand shot to over an amp!  I think something may be wrong with
> > that chip and was the primary reason I was seeing such a high power
> > demand.
> 
> > I have secured some SN7404N inverters and am going to see what one of those
> > does to the circuit.  Hopefully that was the main problem and it all just
> > might still work as-is (with a 7404).  If not, I may still see if the
> > problem is the regulator being pushed to its limit and using a separate
> > regulator might still be an option.
> 
>    You should be using 74LS04 or 74CH04 devices.  (or a transistor and
> resistors)
> --
>    Ron  KA4INM - Youvan's corollary:
>                  Every action results in unwanted side effects.
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