okay, the first problem I had was that the voltage across the power jack terminals is around 9.7 V (instead of 12V), although the wiki says it can vary between 10 and 14 so I didn't worry too much about it at first. I am using the US wallwart bought with the x0xb0x but with a transformer to use with the UK mains, might have anything to do with it?
Now I have finished the power supply and the voltage at pin 3 of J4 is also around 9.7V. The voltage at pin 2 is about one volt too low at 4.4ish instead of 5.333. I wonder if the low voltage I am getting at the jack terminals has anything to do with this?
I've searched and found two people who had similar problems getting 5.333V, although neither mentioned low V at the jack terminals.
http://www.ladyada.net/forums/viewtopic.php?t=608
http://www.ladyada.net/forums/viewtopic.php?t=529
I have checked everything that was suggested in these topics, namely the voltage drops across the diodes in D44-D47 (seems to be roughly 0.6V), re-checked that I used the correct resistors in R3, R4 and R5, and checked that I had used the 202 potentiometer.
Any advice is very welcome, I'm not experienced with this kind of thing at all. The only thing i can think of is that the initially low V is causing this problem, and maybe getting a proper UK wallwart will help.
Thanks!
getting ~4.39 instead of 5.333... help!
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Please be positive and constructive with your questions and comments.
- tospasto
- Posts: 11
- Joined: Sun Aug 05, 2007 5:27 pm
r1, r4 and r5 are fine. r2 is giving me about 0.8K instead of 1. On r3 i am only getting about 4.5K instead of 6.8, but it rises very slowly when i have the multimeter contacts on it, I don't know what is going on there.
cant seem to get a voltage reading between r2 and r1 or r2 and r3, maybe im being stupid...
thanks for your help
cant seem to get a voltage reading between r2 and r1 or r2 and r3, maybe im being stupid...
thanks for your help
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- Posts: 3155
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- tospasto
- Posts: 11
- Joined: Sun Aug 05, 2007 5:27 pm
-
- Posts: 3155
- Joined: Fri Feb 17, 2006 5:35 am
- tospasto
- Posts: 11
- Joined: Sun Aug 05, 2007 5:27 pm
sorry, i think i was doing something very stupid, these should make more sense hopefully
d44 d45 juncture = 3.07
d45 r5 juncture = 3.30
r5 tm6 juncture = 3.30
tm6 r4 juncture = 3.30
r4 d46 juncture = 3.45
d46 d47 juncture = 3.89
d47 r3 juncture = 4.32
r3 r2 juncture = 23.4
r2 r1 juncture = 26.2
doublechecked r4 = 5.6K, r5 = 2.4K, tm6 = 2K
d44 d45 juncture = 3.07
d45 r5 juncture = 3.30
r5 tm6 juncture = 3.30
tm6 r4 juncture = 3.30
r4 d46 juncture = 3.45
d46 d47 juncture = 3.89
d47 r3 juncture = 4.32
r3 r2 juncture = 23.4
r2 r1 juncture = 26.2
doublechecked r4 = 5.6K, r5 = 2.4K, tm6 = 2K
Please be positive and constructive with your questions and comments.