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Studebaker M15A-20 "Mr. Potato Head"

Tuesday, April 23, 2019

Clock Mod/Improvement

I recently installed a car dash into my M15 with all the bells and whistles including a clock. I had rebuilt this clock myself by completely disassembling it, ultrasonically cleaning the parts, and reassembling it. I used the approved clock oil and had it on the bench running flawlessly for several months. I felt it was good to go as it kept time within 5 minutes a month. After installing within a month, kaput. I suspect this is due to the mainspring winding mechanism with those easily burned contacts.

So, what does one do? Taking the clock out for repair is such a hassle I figure I need to come up with a permanent solution to the contact issue. All the engineering solutions I came up with required significant drain current that one would worry about the battery running down. So I decided to use the contacts to my advantage. Instead of the contacts carrying the rewind solenoid coil current, I used the contacts to trigger a MOSFET that carries the the solenoid current. Generally, MOSFETs have a very low off current and one that I had in my stash is very low, low enough where I could not measure any current.

Pros:
1 Contacts last a long time.

Cons:
1. Not stock.
2. Increased complexity.




Here is the before and after circuit:


Modification is as follows: