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HP-42S battery drain
07-14-2020, 04:04 AM
Post: #8
RE: HP-42S battery drain
(07-13-2020 02:55 AM)Marcovecchio Wrote:  Another possibility: the processor certainly has a switching transistor to drive the IR led. Is there an easy way to test if the IR circuitry is ok, if I don't have an IR printer? This transistor might be damaged, and leaking current. Does that make sense?

Do you have an oscilloscope?

If so, you can make a very simple IR detector. You need a photodiode or phototransistor (typically less than $1 here in the US) and a resistor and a few volts from some batteries.

Something like this: https://electronics.stackexchange.com/qu...photodiode
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Messages In This Thread
HP-42S battery drain - Marcovecchio - 07-09-2020, 01:48 AM
RE: HP-42S battery drain - jebem - 07-09-2020, 05:38 AM
RE: HP-42S battery drain - Marcovecchio - 07-09-2020, 12:24 PM
RE: HP-42S battery drain - Allen - 07-09-2020, 01:45 PM
RE: HP-42S battery drain - Marcovecchio - 07-09-2020, 06:09 PM
RE: HP-42S battery drain - Marcovecchio - 07-13-2020, 02:55 AM
RE: HP-42S battery drain - Dave Shaffer - 07-14-2020 04:04 AM
RE: HP-42S battery drain - KF6GPE - 07-14-2020, 05:25 AM
RE: HP-42S battery drain - GreyUser - 07-17-2020, 02:25 AM
RE: HP-42S battery drain - Marcovecchio - 07-18-2020, 04:36 AM
RE: HP-42S battery drain - ijabbott - 07-18-2020, 02:24 PM
RE: HP-42S battery drain - Marcovecchio - 07-18-2020, 08:29 PM
RE: HP-42S battery drain - Marcovecchio - 08-05-2020, 02:56 AM



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