Craig Anderton Frequency Booster vero layout.

[The French connection]

bumpty dumpty!

I've build this according to the first layout on post #1 but add the rotary cap switching feature as on layout #2. When i plug it i've got huge oscillation that can be pitch tuned with the rotary switch in conjunction with the boost pot. Those oscillations can be eard even in bypass but muted. When i touch the input cap (C3) or the first jumper (the longer one), the boost work fine and the rotary select the freq as supposed. I've star grounded the ground on the input sleeve, try the pulldown resistor, search for solder joint but nothing...reflow the all the solder...i got the feeling it's a ground issue or the short jumper under the IC (connecting Pin 1 and 2) must be outside the OpAmp...I'm confused! It's the first time i can debug by myself without help! So someone please help me before i cut my finger and tape it on the input caps!

Here's the reading i got on the IC: TL072
Power supply: 10.37V
Pin 1: 8.15
Pin 2: 8.15
Pin 3: 0.03
Pin 4: 0.00
Pin 5: 0.13
Pin 6: 0.27
Pin 7: 3.37
Pin 8: 10.37

Thanks!

Dan

[The French connection]

Stay tune for more Bump after this messages!

[The French connection]

BUMP!  

Ouch! I swear i'll cut and tape my finger on the input caps...

[The French connection]

Thanks for watching!



Dan from  Bumpost city!

[frequencycentral]

I wish I could help, but the only advice i can give is that if you want your thread to get lots of viewings you need to includ the word 'burst' in the title. 

[fuzzo]

that looks a little bit odd . You should have 4V5 to the input of the opamp (bias) and you haven't.

When one my circuit doesn't wrok I check the bias and if it's here where it does. look the R3/R4 jonction if you got bias.


Have you tried another op-amp ? (maybe a stupid question but sometime I spent a lot of time searching where I made a mistake when I realized I've a bad chip plugged into the circuit, I change it and my god! that works ! )

What's "burst" ?

[The French connection]

I wish I could help, but the only advice i can give is that if you want your thread to get lots of viewings you need to includ the word 'burst' in the title. 

Thanks Rick! The problem is not the viewings, it's the replying...but i guess adding 'Burst' could help on this too!

that looks a little bit odd . You should have 4V5 to the input of the opamp (bias) and you haven't.

When one my circuit doesn't wrok I check the bias and if it's here where it does. look the R3/R4 jonction if you got bias.


Have you tried another op-amp ? (maybe a stupid question but sometime I spent a lot of time searching where I made a mistake when I realized I've a bad chip plugged into the circuit, I change it and my god! that works ! )

What's "burst" ?

Hi Fuzzo! Yeah i've tried another opAmp and the one install is known to work since i've test it on my breadboard. But you seem right about the bias, at least i should have 5.19V )10.37V/2) and i have 8.15V...hum! Good catch! I look this way!

Seriously, i've mess with it again but still have those oscillations that goes from ''motorboating'' to ''whistleling'' depending on caps selection. I got the feelin that the way i've wired the rotary with all those caps tied together is the issue. It's crazy since when i touch the board at the input cap with my finger, it works fine...so i tought ''ground issue'' but i've redone all those ground 3 times  with 2 different configuration...and tried a battery instead of PS...

Burst est synonyme d'explosion ou éclatement...il fait référence au ''Busrt box'' thread. Si tu ne l'a pas croisé, ça ne vaut pas vraiment le détour...mais il y a quelques bonnes blagues

Merci

Dan

[fuzzo]

mumm strange affair.

That looks like a ground issue yeah. If I was you I remove the cap selectro and put just two caps (I don't think that problem comes from it but that will reduce the problem possbilities. 

Have you see if your strips aren't connected by a soldering or , even (I made this expérience) with a little metal brand (coming from the wire, when you break it that thing can  stay on the strip and make some issues). Anyway , maybe you've already check that .

After dinner I'll check your layout and bring you  my little help.

[slacker]

The layout looks fine to me. As you haven't got half the supply voltage on pins 3 and 5 of the opamp something is wrong there. If you've socketed the opamp remove it and measure the voltages on pins 3 and 5 of the socket, if you don't get half the supply now then something is wrong with the connection of R3,R4 and C5 or you've used a wrong component value. If you do get around half the supply then check that you've got connectivity between pins 1 and 2 of the opamp, if you'd missed that jumper then you'd get all manner of weirdness. Like fuzzo said I would try removing the switch and just use 2 caps to get it working.

[The French connection]

Thanks Guys! I really appreciate your Help! I've finally concluded that i hate debugging so i've stopped wasting my time and get the desolder braid out, save some parts and rebuild the whole thing according to the last layout. Did'nt take chance and socket the freq caps...Everything works fine now! This layout is now verified and the rotary is working fine. Did'nt find the mistake on the other layout tough, so i've removed it. It's a nice booster finally, pretty usefull and versatile. The last setting with 0.0022 caps are more high treble boost than ''higher midrange'' (10 kHz).

Thanks again! 

Dan

[Baktown]

Hey guys,

I know this thread is old, but I ran across it last night and am curious to build it using vintage caps salvaged from an old tube organ.

My question is on the 6 way rotary switch, all the caps are marked C1 or C2.  Which values go on which lug?  Sorry for the easy question, but I just don't understand it.

Thanks,

Rick J

[Baktown]

Anyone?

Wondering why the caps are all marked C1 or C2, even though they obviously have different values and need to be in certain places to work.

Any help would be appreciated!

Rick J

[The French connection]

Hello Rick,
   i gotta admit that's not really clear. The caps just have to be paired and opposed... So supposed C1 at the far left is 0.22µf, then C2 at the opposite (far right) should also be 0.22 µf...I know it's not clear yet

I can do better. If C1 at the left is denoted, lets say A, the next one is B, the next one counterclockwise is C and on and on 'till L for the last C2 at the left, then A and G are 0.22 µf, B and H are 0.1 µf, C and I are 0.022µf, D and J are 0.01µF, E and K are 0.005µf and finally, F and L are 0.0022 µf.

Sorry if it's not clear...it's cultural, i'm a french canadian!

Salut.

Dan

[wrangles]

Anyone?

Wondering why the caps are all marked C1 or C2, even though they obviously have different values and need to be in certain places to work.

Any help would be appreciated!

Rick J

they're all marked C1 and C2 because the original schematic for the circuit doesn't have a switch and is wired to provide only one possible frequency boost. You would just choose which freq you wanted to boost and then permanently wire in two caps (of the same value) for C1 and C2. Nobody bothered to rename all thew caps for switchable frequencies b/c people are lazy and also since the caps all the serve the same function and are more or less located in the same place, it just seemed easier to refer to those two caps by the same moniker (though it might have been easier to call them something like C1a/C2a,C1b/C2b or something). just make sure each C1=C2.

[Baktown]

THanks!

[Xavier]

So resurrect an old topic..............I need a booster for solos, but what I need is something that boosts 500 Hz (fixed frequency), so this one looks like a suitable candidate.............what C1 / C2 values should I use , 47n, 56n, ? How to calculate this ?

One more question............if I skip the volume control, with the boost knob at zero would I have unity gain ? I'd like to build a one knobber............

[Paul Marossy]

So resurrect an old topic..............I need a booster for solos, but what I need is something that boosts 500 Hz (fixed frequency), so this one looks like a suitable candidate.............what C1 / C2 values should I use , 47n, 56n, ? How to calculate this ?

Not sure how to calculate that, but I can interpolate from my PCB layout here that's it probably going to be something like what you suggest, a 0.047uF or a 0.056uF cap. Maybe even a 0.068uF cap. One of those three ought to get you the desired result.

[Xavier]

Thanks Paul !!

[Paul Marossy]

No problemo. 

[amonte]

I was looking at this schematic and I was wondering - would it be possible to swap the 6 position switch with a dual gang pot and have each side act as a blend between a .22uF and .0022uF cap? 

Basically, doing Joe Gagan's input blend cap mod for both C1 and C2.  Would that work?