Wednesday, October 28, 2009
UV916 tuner receiver based (part 1) - Power supply
For the UV916 tuner one needs an 33v power supply. That's a small problem, my bench power supply only has 12v (more or less). Digging for an easy step up converter (read: search for what components were available locally) I found the MC34063 IC that my local electronic shop stocks as KA34063. After reading the datasheet I came up with a schematic.
Now it's a question of start dismantling some computer power supplies to find the 170 microH inductor since I don't feel like't to make one. I still don't have the IC so for the first time the schematic come first!
The local store doesn't stock the BYV10-40 diode but stocks the 1N5822, they look similar (10-20% values) in the datasheet so I will give it a try.
This is my first "switched" power supply so anything could hapen!!!
Replaced the 47K resistor by an of 33K and the 1850 ohm for an 1K2 in series with an 220ohm variable pot.
Diode was replaced by an 1N5819.
I did wind, after all, the toroid, it was salvaged (along with the output 200V!!! capacitor) from an old computer power supply and has 82 turns of 24swg wire on a yellow core... probably less turns would work also.
The 0.22 Ohm resistor was made winding around 40cm of wire.....It works.
Placed an 56k "bleed" resistor in parallel with the output to discharge the capacitor.
After following the data sheet on the MC34063 and making the schematic I found an online development aid for the IC at: http://www.nomad.ee/micros/mc34063a/index.shtml