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ginji
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Posts posted by ginji
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Ante: I think you misunderstood me, i'm not trying to replace a part, rather get one to so i can use it as a precationary thing :)
MP: First i've heard of NTE, and looking on the distributor list only lists one in Queensland.... a good 600k's away from me at least, with no option of ordering over the net.
Thanks for your help guys, i may go try and figure out a non-darlington one -
Ante: It's there so i don't fry the mother board of my computer and everything else with it if it stuffs up
MP: I've looked at the datasheet and the 4n32 is the only part i have found that is close, otherwise i wouldn't be asking :) -
I'm after a part that is close to the 4n32 (Fairchild) or TIL198 (TI - obsolete) optocouplers... I can get parts from TI, maxim-dallas and national directly but not fairchild :( and the TIL198 is unavialable... does anyone have an suggestions for a replacement IC?
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thats cool, but i like my weller better :P
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Hey MP, i've built the power supply, and it works, and i should be able to take it up to the uni for testing with a cro later... will let you know what happens
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it sounds like you've got some oscillation in the circiut somewhere. Check your rectifier, but apart from that, i'm not sure what else could cause it (maybe a short somewhere feeding back?)
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another suggestion that has been made is to wire 2 pots in series, one the recomended resistance, and the other 10% for fine tuning
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C1 upgrades to 4700uF or higher, 10 000uF is suggested i believe
The rectifer bridge as a single 10A or higher part, this way it can be attached to the side of the case
I'm changing Q2 from the 2n2219 to a BD139 (you can use a BD137)
WARNING! the pins on the BD139 is different to the 2n2219
Feed back resistors (R4/5/6) to metal film type for the lower tolerance
Other suggestions (not made in this thread, but the other one)
Replace R2 and R3 with 1/2W resitors
R7 with 10W resistor
R1 with 2-3W
P1 is a many-turns wire-potentiometer (10 turns), and P2 is a "cermet" single-turn -
try this: http://www.minidisc.org/headbanger.html
if you can make a PCB for it, the circuit is about the size of a 9v battery (slightly larger) and it works really well (by that, low distortion, high amplification) I've built some before, quite easy to get the parts, and easy to make -
ginji, thanks for the update on the project. I would also be interested in an easy method of building transformers if your dad would not mind sharing. There is a post and an article on this website but it is very difficult. If you could do this, please add as a new post so that the subject is easily found by others.
Thanks!
MP
it's been a while since he's actually built a transformer (last time was at least 16 years ago if not more) so i think what ever he can actually remember is a bit out of date. The article in articles section explains the process quite well (from my understanding of it) although i can understand that people get confused by i
the printed circuit board i'm using was made by my uni (yay for my uni) using protel and some CAM stuff (CAM is computer aided manufacturing) so it isn't etched but has the copper round the tracks cut away. -
hey all
I am/mostly have built this power supply, but i've made some changes along the way:
C1 is now a 4700uF 50V (Maybe change this later...)
The 3 feedback resisters are metal film (R4/5/6) for the lower tolarence (1% compared to 5%)
And i'm changing Q2 to a BD139 (if you want to make the circuit 5A then you'll have to change Q2 to one which dissapates more heat, BD139 can also be connected to a heat sink)
The transformer i'm using is a half-half (half the primary and half the secondary on each side), not sure about the VA, as it is one which my dad made himself a while ago.
I should be able to get access at uni to a oscilloscope, and test the supply for any problems.
darlington optocoupler
in Datasheet/Parts requests
Posted
thanks for the effort you put in guys :)
the closest part i can get is a 6n138 - http://www1.jaycar.com.au/products_uploaded/ZD1940.pdf
but i dunno if it's compatiable