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PMP 5 Logic Probe

 Davy Dick's  PMP 5 Logic probe is a really useful piece of testing gear to establish the logic output of a 5 Volt circuit.  The original kit is built on stripboard and requires three tracks to be cut which can be problematic for some.



It may be useful, particularly at exhibitions, to show the status of a digital signal being output from one PMP Kit to ascertain how the next circuit should respond.

 A good example of this would be PMP4a (Shuttle Add on) driving PMP 18 (Ezy-Points).

To avoid any confusion of polarity, I arranged for the Power and Logic headers to be made available at both ends of the circuit and colour coded them as follows.

Red  + 5Volts  ;   Black 0 Volts common ground  ; White  - Logical Output to be tested

All the tracks in my version are continuous and will fit on the same board provided in the kit.

Obviously, the component layout have been changed slightly but still follows the original circuit diagram.

A common stripboard size is 25 pin x 9 pin which is perfect for cutting symmetrically  into two 12 pin x 9 pin boards.

With only 4 resistors, a green LED, a red LED, a BC557 (PNP) and BC547 (NPN) transistor, the component count is very low and cheap to make.

I can send anyone the layout diagram if required. I drilled a couple of mounting holes but a 3D printed mount could be used instead.


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