Regulator runs cool now!

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Regulator runs cool now!

Postby Quaxo76 » Oct Sat 20, 2012 5:16 am

I've always had problems with the regulator's temperature, it would get very hot very soon. The power supply I was using was rated 8V, but was putting out about 8.5, so that's a lot of power being converted to heat. The only other power supply I could use was a 6V, but the voltage was too low for the 7805 regulator.
So here's what I did: I replaced the 7805 with a drop-in replacement, the 2940-5. which has the same size and same pinout, but lower drop-out voltage.
Then, I bought a small step-down switching regulator: ... 682wt_1388
which is extremely cheap, and put it between the power supply and the Kim, and regulated it to the lowest voltage that would give me a good, stable 5V after the 2940. Turns out that the 2940 is already happy with 5.8V.
So now the 2940 only has to dissipate to heat 0.8V instead of 3.5, and even after hours of use it's just barely warm - much cooler than the 6502.
The switching regulator is just cold, as it has a great efficiency.
So now I'm happy and can keep the KIM on for hours without worries! :) Now I'm doing the same thing to the Altair.

Of course now with the 2940 in place of the 7805, I could even just use the 6V supply and avoid the switching regulator, but this way I have some more flexibility.

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Joined: Sep Tue 25, 2012 5:50 pm

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