L293D used to reverse motor direction 7.8 vdc

[Doddy]

I'm starting to back away slowly from this thread as it's clear that you haven't got a lot of experience with electronics... happy to take this PM as there's a lot of alignment needed here to get us on the same page/understanding which is kind of off-topic for the majority of posts on these forums.

Firstly, please give me/us the photo that I asked for. At the moment we're trying to guess a lot about a fairly unconventional lash-up that you've done. Even if this just corroborates your explanation it removes a huge amount of uncertainty from this thread. I acknowledge what you say about any image being unclear - but it's clearer than my crystal ball, believe me.

Now, earlier, I asked about measuring current (during the CCW/CW operation), but you've reported a voltage, labelling it current. Current and Voltage are different quantities (there's usually a relationship, however), but measuring current is done differently - selecting the current-range on a DMM and placing the meter leads in SERIES (rather than parallel/across) the device being measured. IMPORTANT: a DMM measures current by measuring the voltage across a precision, very low value resistor internal to the DMM... which is why after measuring a current you really should recover the DMM to set-up to read voltage, because if you next try to measure a voltage with the DMM configured for current you will present that very low value resistor across the meter leads and likely pop the fuse in the DMM, or otherwise destroy something usually expensive. If you want any information or advice on measuring current, or anything else, PM me. (it's a shame I can't / can't figure how to include images in PMs... may have to revert to email).

The reason that I was asking you to measure the current between the 7805 and the L293D was to understand if the 7805 was entering an overcurrent protection mode... a necessary step in understanding what should otherwise be a very straight forward circuit. That you dropping the voltage (not current) to 3.8V is sinister and must be resolved. It would suggest the L293D is pulling more current than the 7805 is designed for which either indicates a failed L293D or a short in your wiring.

EDIT: One simple question: Is your goal here to understand and to develop your solution?, or are you just looking for something that works to get you moving onwards? Genuine question... if the latter then you probably want a turnkey solution rather than a protracted diagnostic thread.

[cropwell]

I can understand your need to have the circuit as small as possible, but I would advise building it on a breadboard first to check it works.