[Test-Equipment] Question Regarding Fluke 8050A

[KA4INM]

   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.