12v to 9v Transformer?

[JFrankParnell]

Please move this post if neccessary...it is an amp that I want this for, though.

So, on the FrankenHog guitarnuts2.proboards.com/index.cgi?board=Amps&action=display&thread=5667 , I have a 12v amp and a 9v amp glommed into one. Which means I have 2 wall warts, 2 wires going to the amp.

Since I have a big 12v supply, couldnt I mount a transformer in paralell, and step down to 9v to feed that section? A quick google and a short convo with the salesdouche down at the shack didnt really inform me.

And of course, would having a transformer in the amp be problematic? noisy?

[frequencycentral]

7809 voltage regulator is good for 1.5A. Just put a big butt electro cap to ground on the input and another on the output.

[JFrankParnell]

umm...
www.researchcell.com/general/7809-pin-and-circuit-diagram/

Google didnt have anything good for big butt electro cap ;D
But I see in that diag, the caps they have.

Now, I still dont get the ground concept where there are different voltages and circuits all using the same ground? That seems weird, like the different voltages would get mixed up, lol. The power jacks on the amps are plastic, and isolated from the chassis apparently. Whereas the audio jacks on the hog seem to be grounded to the chassis, but not on the Roland.

from the site above: Would anyone like to comment on the relevance of this stuff, wrt amps (&specifically mine)?

It is wise to use two .1uF capacitors on both input and output sides to filter any ripple or distortion in voltage but it is not necessary. In the image, you can see that 12V are being supplied on the input side of 7809 but the out put side of 7809 is outputting Regulated 9V. As long as the input voltage remains above 9V, output voltage of 7809 will remain smooth and regulated.
Please note that input voltage of 7809 can be up to 23V but under my experience, it is wise to avoid input over 15V. 7809 is claimed to output 9V and almost 1.5A Current but again, I have experienced that we should not put a load over 9V and 1A on it. Since we are using it in power supply, the transfer of power will result in heat output. We will need to use a heat sink with 7809 otherwise this heat can damage it. It is advised to use a 1A fuse on the output side of 7809 and a 1.5A fuse on the input side of 7809 to avoid damage in case of short circuit.

[frequencycentral]

[quote author=jfrankparnell board=Amps thread=5668 post=53766 Now, I still dont get the ground concept where there are different voltages and circuits all using the same ground? That seems weird, like the different voltages would get mixed up, lol. The power jacks on the amps are plastic, and isolated from the chassis apparently. Whereas the audio jacks on the hog seem to be grounded to the chassis, but not on the Roland.
[/quote]

Ground is ground is ground. Ov. Got a DMM?

[ijustwannastrat]

Apr 13, 2011 14:10:46 GMT -5 frequencycentral said:

Ground is ground is ground. Ov.

Until you're an electrician. Then ground is grounding but not grounded, but grounding and grounded are the same (in your panel). Then you have bonding... ;D

[ashcatlt]

Does the 9V amp already have on-board (as opposed to "on-wart") regulation? Or, does it actually have any components rated low enough voltage where 12V would hurt them? It's quite possible you can just use the one PSU, assuming it can provide enough current.

[JFrankParnell]

the 9v has a small 200ma wall wart. the 12 a large 1500ma halfway on the cord. The 9v has roland/boss modeling circuit, lotsa chips in there.

[sirma]

Is it still noisy? In the figure, I saw two caps on the either side of the IC which should work as a noise filtering circuit I think. Ground is always one point where all the circuit meet so that is not a problem. It’s been some time since it was posted so were you able to find any solution for it?

circuit board assembly

[JFrankParnell]

I never did build this transformer thing, but I still think about it alot It could still happen!

re: noise, not having built it, idk about the noise, but if those caps on the sides do what you say, that'd be good. I currently have both wall warts wired (baling wire) to the speaker frame and stuff, with a light extention cord coming out. Not unduly noisey.