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Dynalo (Rev.C) construction thread
Jul 30, 2005 at 2:01 PM Post #46 of 188
Quote:

Originally Posted by Garbz
Personally I've gone overbaord putting 6x 470uf 16v caps on each board.


16v caps? Aint that cutting it a bit close?

And wow, 470uf? Thats quite a bit :p

Rob.
 
Jul 31, 2005 at 12:52 AM Post #47 of 188
it is seeing how there's 16.5v going into them. But so far every dynalo i built has survived. I doubt the caps will survive for their rated life span though. Plus 25v ones didn't fit
wink.gif
 
Jul 31, 2005 at 6:29 AM Post #49 of 188
16v 470u Elna Simlics. The 25v 470u don't fit. But I believe the 220u do. Pity they aren't stocked where i'm shopping.
 
Aug 11, 2005 at 7:44 AM Post #53 of 188
Quote:

Originally Posted by silvalis
Are there any other recommended alternate BJTs to replace the 2SA1015 & 2SC1815 other than MPS8099/8599?


Reasonable substitutes are BC327/337 or BC550C/560C. Note that these have different pin-outs than the 2SA1015/2SC1815, so you will have to orient them on the board differently.
 
Sep 11, 2005 at 3:59 AM Post #54 of 188
i recall reading that there is a pair of resistors to replace with a trimpot to eliminate/reduce the need for transistor matching.

anyone know which pair?

also, am i correct in my assumption that this can be COMBINEd with the dc offset servo? i hope to finish my build, dial in (servo not connected) and then connect the servo. after that the servo will have a minimum of work to do only correcting for parts that age, and whatnot.
 
Sep 11, 2005 at 4:05 AM Post #55 of 188
Quote:

Originally Posted by nikongod
i recall reading that there is a pair of resistors to replace with a trimpot to eliminate/reduce the need for transistor matching.

anyone know which pair?

also, am i correct in my assumption that this can be COMBINEd with the dc offset servo? i hope to finish my build, dial in (servo not connected) and then connect the servo. after that the servo will have a minimum of work to do only correcting for parts that age, and whatnot.


The 500 ohm resistors.
 
Sep 11, 2005 at 4:07 AM Post #56 of 188
you =the man.

i bet there are even pads on the board for that specfic purpose...

edit: a further inspection of the board, and schematic reveals that indeed pads for just that do exist. bonus round.
 
Sep 11, 2005 at 9:57 AM Post #58 of 188
define signal path. I wouldn't use these pots as a volume control, but here they are only really adjusting the bias current for an LED.
 
Sep 29, 2005 at 2:37 AM Post #60 of 188
Hi folks,

Got the dynalo amp to the startup stage. I had +5mv and -5mv initial dc offset. I then zeroed it out with the trim pots.

I used a 100 ohm resistor for r19 and 1kohm for r16, trying to get a gain of 11. The voltage across r19 is 0.417v, voltage across r23 etc is about 0.227v, these do not match the guide...

Then I put in the opamps and the offset steadily rises to about 3+ mv after about 10 minutes. Is this normal or should it regulate down below 2 or 1mv?

Any suggestions.

Also, for the dynahi psu, do the regulators need to be electrically isolated from the heatsink(i.e. from each other). If so, what insulator do you use to do this?

Thanks
Pete
 
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