Hi everybody,
New to this site and Im working on a EA TREMOLO pedal. So far so good but I had a question about using tantalum caps which are polarized for c6 7 and 8. I am using .62 uf caps to get a little faster rate...but Im unsure if I am putting them on the board the right direction.
This is the layout I am using.
http://www.google.com/imgres?num=10&hl=en&safe=off&biw=1366&bih=616&tbm=isch&tbnid=nS-mje4bKqb-HM:&imgrefurl=http://www.aronnelson.com/gallery/main.php/v/DRAGONFLY-LAYOUTS_0/album19/album145/EA_TREMOLO_VERO.gif.html&docid=thoYkHl9xOQSEM&imgurl=http://www.aronnelson.com/gallery/main.php%253Fg2_view%253Dcore.DownloadItem%2526g2_itemId%253D11001%2526g2_serialNumber%253D2&w=640&h=523&ei=hW2IUJSOFsybjAL60YFg&zoom=1&iact=rc&dur=5&sig=113765772895616441647&page=1&tbnh=178&tbnw=217&start=0&ndsp=15&ved=1t:429,r:4,s:0,i:84&tx=132&ty=62
Sorry for the long url its the aaron nelson modifed ea tremolo layout.
I put all three caps with the positive terminal facing to the left(toward transistor) but am concerned that the ends of these rows are tied together and might send voltage backwards through them.
Also, I think the led on the board is shown backwards as it should be.
Thank you....
Welcome.
So, here is the schematic from which that layout is taken:
http://www.home-wrecker.com/eatremolo.html
[That vero layout gives credit for the schematic to Runoffgroove but the ROG guys moved it to Home-wrecker. Anyway...]
If you scroll down the page you'll see a perfboard layout for the circuit.
Doing my best to translate from the perf layout to the vero layout, it looks like the cap labeled as "C8" on vero should have its negative lead connected to the negative lead of "C6." So, if you did in fact mount all 3 polarized caps with the positive lead facing Q3, then C8 should probably be reversed. At least I think so.
I've built 2 of these, and I'm pretty sure I used polarized caps in one and NP in the other. In both cases I followed that perf layout, and in both cases the circuit worked.
Good luck!
Thanks Jim,
Ill switch that on around and looking at the perf layout I think the led shown is backwards in the vero layout Im using.
Quote from: JasonJohnson86 on October 24, 2012, 08:35:48 PM
I think the led shown is backwards in the vero layout Im using.
It looks that way to me. LED+ should connect to R9, the 10k current limiting resistor. LED- should connect to the collector of Q3.
If you are still having trouble getting that layout to work, you are not alone. I tried this layout and failed to get it to work. I then found a number of other similar accounts of problems with this particular layout.
Both |\/|ark's (http://tagboardeffects.blogspot.co.uk/2012/02/ea-tremolo-modified-rog.html) and Harald's (http://www.sabrotone.com/?p=2975) vero layouts do work. Either way, this circuit is tricky to bias, so use a multi-turn trimmer.