another thing i thought about is that in the 303, the ac from the transformer is rectified by only one diode. while the xox rectifies in both ways. so that should leave half wave in the 303 and full wave in the 303. am i wrong?
i thought about removing d43 in the rectifing bridge of the xox to make it halfwave, but is d43 part of the voltage doubler???
aminoacid wrote:i would listen to anybody who is giving advice on this, im not to good with it, so ill pass the removal of d43 :)
i was thinking that i could get closer to the 303 by using half wave rectification. similar circuit with similar rippel if you follow me?!
i tried the 15V zener from r1-c5 to ground. but it didnt work. the voltage didnt get far and the zener got very hot before i pulled the power.
maybe a regulating circuit is required like in the 303... a transistor sinking the voltage doubbler perhaps...
Altitude wrote:This might be useful: viewtopic.php?f=12&t=17037&p=86295
evostars wrote:Gompie, where did you buy that R-78B5.0-1.5? Looks good to me.
gompie wrote:evostars wrote:Gompie, where did you buy that R-78B5.0-1.5? Looks good to me.
You can order it online from RS or Conrad. Mind you that it is not a very cheap component.
evostars wrote:Thanks, but RS? whats that? oh I guess Radio shack?
gompie wrote:evostars wrote:Thanks, but RS? whats that? oh I guess Radio shack?
Nope, RS-components is like Farnell.
For cheap components online in your area I'd suggest dickbest [dot] nl
Funny name, but the prices of their components and shipping costs are also a joke :)
I would have bought the R-78B5.0-1.5 regulator there, were it not that they did not have it....
One of the few companies that offers the option to ship your components via letter post instead of charging for a complete package while ordering one or few small components!
aminoacid wrote:wouldnt a 5Vac adapter be better by the way???
closer to 15V after the voltage doubler and less heat loss in the 5v reg.
MMM wrote:I'm a bit late to the party, I know. Last week I was thinking pretty much along the same lines when getting into the power supply issue.
I wonder what the rationale was behind the design (as a whole). After all, using AC power adapters is comparatively uncommon (there are many more devices using DC adapters).
The power supply in the original 303 and 606 used a very different design for the "early stages". It involved an (impossible-to-find) DC-DC-converter. But theoretically there are modern substitutes for it.
Edit: I've also been wondering why the input to the first opamp is always below 5.33v for the output to reach 5.33v. On the power supplies I'm having around at the moment the input is about 5.20v but the output is 5.33v. Theoretically the opamp should be just a buffer, right?