Noob Question - Ep Boost Breadboard

[BlackLlama]

Hi everyone

I had some parts laying around and thought I'd give a crack at breadboarding the EP Booster. I used this schematic, which from what I understand looks like the standard one available over the web.




This is my second attempt at breadboarding a Pedal. The first one was an EHX type boost (no problems with that one). I've checked for continuity with my Multimeter to check if everything is indeed connected and tried swapping out parts looking for bad ones (just in case) but from what I understand that's not the issue. I also made an audio probe and the sound seems to cut off at the red points in the image. Notably at R5 and after C2. Signal comes back at the collector of Q2 but then cuts off again.

I haven't wired in a switch yet and I've skipped the additional treble/bass switching. Circuit is powered by a new 9v. "In" and "out" share a cable for ground connected to board ground.

Again this is the first time I attempt something like this. I have some really basic understanding on things which is why I thought I'd ask here. It could be the Q1,Q2 pinouts, wrong connections or something really obvious to you guys that I just can't see on my own. Maybe I was a bit over ambitious






On a side note. Is the Audio probe signal supposed to cut off at the after the R5 section towards the D1?

Thank you in advance and if you need more shots of the breadboard or anything else from me that would things easier, I'd be happy to share more.

[Jolly Jimmy]

Just had a quick look, R2 should be 33K, you have a 1M in there.

[Jolly Jimmy]

First off, this may seem blatantly obvious but I can't see any supply connected to the power rails.

EDIT: Ignore most of this next part, my mistake!

Next, I see the only thing you have making a circuit is the LED and its CLR. Nothing else is connected to the positive rail at all!

You have R5 and R9 connected together which is partly correct, they are on the schematic, but only in the fact that they are both coming off the + rail, which you don't have going on.

You have Q2's pinout mixed up. Flat side facing you it goes EBC.

I'm guessing that's not all but I should probably stop here

Go back to the schematic and follow it carefully. The entire top line is the + side of the power supply! You can leave out D1, R14 and the LED. No need for them here. And C5 should straddle the power supply.

[thermionix]

Next, I see the only thing you have making a circuit is the LED and its CLR. Nothing else is connected to the positive rail at all!

No, it's going through D1 to R5 and C5, etc.

I think you're right about Q2 being backwards though.  Easy fix!

[Jolly Jimmy]

Next, I see the only thing you have making a circuit is the LED and its CLR. Nothing else is connected to the positive rail at all!

No, it's going through D1 to R5 and C5, etc.

I think you're right about Q2 being backwards though.  Easy fix!

Ah yes indeed that explains a lot! oooops

[Tony Forestiere]

First off, this may seem blatantly obvious but I can't see any supply connected to the power rails.

Neither do I. Check for supply voltage on one side of R5 and R9.

[BlackLlama]

Thank you for all the comments guys!

First off, this may seem blatantly obvious but I can't see any supply connected to the power rails.

EDIT: Ignore most of this next part, my mistake!

Next, I see the only thing you have making a circuit is the LED and its CLR. Nothing else is connected to the positive rail at all!

You have R5 and R9 connected together which is partly correct, they are on the schematic, but only in the fact that they are both coming off the + rail, which you don't have going on.

You have Q2's pinout mixed up. Flat side facing you it goes EBC.

I'm guessing that's not all but I should probably stop here

Go back to the schematic and follow it carefully. The entire top line is the + side of the power supply! You can leave out D1, R14 and the LED. No need for them here. And C5 should straddle the power supply.

I realised I had Q2 backwards right after posting on here but ofcourse that alone didn't fix anything!

I am going to ask something which probably will send me back to Electronics 101 books (no problem whatsoever) but here it is...Since the anode of D1 sees the positive rail why do R5 and R9 also need to connect to positive? Don't they see + comming from D1?

Also, I added this to the schematic which made for signal flow everywhere except for R5,R9 and Q2 Collector



Again thank you for all your comments. I will read more on the basics and take a crack at it later today.

[duck_arse]

I think your R10 is missing the base of Q2 by one row of ties. if I were you, I'd take those two strips of three socket-pins off the board, and throw them as far as I could. on the breadboard, you don't need sockets, every connection is a socket.

also - voltages. always post voltages, cause we'll ask for them anyway.

has anyone welcomed you to the forum, yet?

[Jolly Jimmy]

That's my mistake, I was ignoring that part of the circuit as unnecessary, and became "blind" to it, so no problem there! (see my edit comment above).

At the risk of making another silly mistake, I think Q2 is not simply backwards, but all the pins are in the wrong place. I see the + rail connected to B instead of C, R10 E instead of B, and C8 and R11 to C instead of E.

[BlackLlama]

I think your R10 is missing the base of Q2 by one row of ties. if I were you, I'd take those two strips of three socket-pins off the board, and throw them as far as I could. on the breadboard, you don't need sockets, every connection is a socket.

also - voltages. always post voltages, cause we'll ask for them anyway.

has anyone welcomed you to the forum, yet?

Thank you for your comment. R10 is connected to Q2 Base. It probably looks weird on the shot because the resistor leg is a bit bent towards the collector.

If by voltages you mean 9 or 18 then it's  9v for this one.

And no I haven't been officially welcomed but you guys answering my mess is a warm welcome in itself!

That's my mistake, I was ignoring that part of the circuit as unnecessary, and became "blind" to it, so no problem there! (see my edit comment above).

At the risk of making another silly mistake, I think Q2 is not simply backwards, but all the pins are in the wrong place. I see the + rail connected to B instead of C, R10 E instead of B, and C8 and R11 to C instead of E.

My mistake on the Q2 thing. Forgot to mention I replaced the 2n3904 with a 2SC1815 which from what I understand makes the connections correct unless there's something I'm not seeing.

https://www.mouser.com/ds/2/68/2sc1815-1149989.pdf

As is (with the added components I posted) what confuses me is that I am not getting any guitar signal with the Audio Probe after R5,top of R9, R9 R8 R10 C7 junction but comes back at the bottom end of R10 and flows through Q2. Base and Emitter of Q2 have signal but not the Collector. Are there any parts of a pedal circuit that aren't supposed to produce sound apart from Ground? I asking this for peace of mind mostly (and knowledge ofcourse) so that I can redo the thing with clearer mind.

I think everything is leading to me redoing the process. This morning I had audio signal cut-off only on the R5-R9 connection and now without touching anything I also loose signal at the 8,9,10 juntion. Maybe something moved on the breadboard or who knows but it's getting confusing enough that it only makes sense to start over

Sorry if my info is messy. First time posting about anything electronics related on a forum.

[duck_arse]

official - welcome.

the transistor swap is a nice trick - but you now have the base where the emitter should be, ie backwards. and when we say "voltages", we want the battery/supply voltage (as measured) and the voltages on all the IC and/or transistor pins (with pin numbers/names). take all voltages with no input signal.

[thermionix]

2SC1815 pinout is not the reverse of 2N3904, it's a different order.  ECB instead of EBC.  Why not just put the 3904 in facing the other way?

[BlackLlama]

2SC1815 pinout is not the reverse of 2N3904, it's a different order.  ECB instead of EBC.  Why not just put the 3904 in facing the other way?

Didn't have a 2n3904 available and after looking at a few schematics the EP Booster seems to use the 2sc1815. Could be wrong thought.

official - welcome.

the transistor swap is a nice trick - but you now have the base where the emitter should be, ie backwards. and when we say "voltages", we want the battery/supply voltage (as measured) and the voltages on all the IC and/or transistor pins (with pin numbers/names). take all voltages with no input signal.

Thank you for welcoming me

Voltages are at the moment (and after redoing it since my first post)

Supply 9.53

Q1 -2N5457
1 7.15 D
2 0.92 S
3 0     G

Q2 - 2SC1815
1 2.44 E
2 8.83 C
3 2.40 B

What troubles me is that even though it gives off sound and sounds good as a pedal, The resistors that are comming off of the power input section are not giving of any sound (R5 and R8 R9 R10 C7 junction) with the Audio Probe when I connect a guitar to it. I don't know if this should be the case or not.

[duck_arse]

at the top end of R5, and at the bias voltage point, R9//R8//R10//C7, there should be no signal. and AC will be coupled to ground via either C7 at the bias, or C5 at the supply.

[BlackLlama]

at the top end of R5, and at the bias voltage point, R9//R8//R10//C7, there should be no signal. and AC will be coupled to ground via either C7 at the bias, or C5 at the supply.

Thank you! I was wondering about that one. I need to read up on biasing. I knew about the AC part but the first part of your answer didn't even come to mind.

Re-did the whole thing just now and made a more easy to look at and cleaner version. Sounds good but I don't really have any recent memory of how the EP Booster sounds. Also made a FF variant (how original!) to get my mind off the EP Booster before coming back to it.

One last thing. Any pointers as to where I should start reading to understand Transistor voltages better? I see lot's of people having issues and being asked voltages. Don't really understand why other than just assume randomness.

[antonis]

And no I haven't been officially welcomed

Stephen IS forum's official wellcomer..!!! 

(but you have to wait for a global/integrated wellcome 'cause some guys, like His Highness Sir Mike, only wellcome in MosFet booster alike threads..)

Any pointers as to where I should start reading to understand Transistor voltages better? I see lot's of people having issues and being asked voltages. Don't really understand why other than just assume randomness.

Ohm's law (toghether with Kirchoff's Current & Voltage laws) leave no room for randomness...

[BlackLlama]

And no I haven't been officially welcomed

Stephen IS forum's official wellcomer..!!! 

(but you have to wait for a global/integrated wellcome 'cause some guys, like His Highness Sir Mike, only wellcome in MosFet booster alike threads..)

Any pointers as to where I should start reading to understand Transistor voltages better? I see lot's of people having issues and being asked voltages. Don't really understand why other than just assume randomness.

Ohm's law (toghether with Kirchoff's Current & Voltage laws) leave no room for randomness...

I feel warmly welcomed already

Well I am reading on Electronics but really understanding a circuit with ICs and Transistors mixes it up alot for me right now. I do consider myself a baby on this subject at the moment but I hope to get there one day

Oh and by the way, Greetings from Thessaloniki

[antonis]

Oh and by the way, Greetings from Thessaloniki

Oh by the way, no need to greet here..
(if you live on East side, just open your window and wave at me..) 

P.S.
Things are simple if you make some simple considerations..
(like taking apart transistor legs and face them as diode-connected loops..)

[duck_arse]

[he waves to antonis] - we don't have a wavey-emocon? you mean east side of australia?

I should stay on topic, so I'll say - bread up a big-muff pi circuit, with your assortment of funny transistors. then go thru and work out what voltages are wrong and causing the circuit to mis-function.

[antonis]

If I ment East side of Australia, BlackLlama should have a VERY long arm.. 

To also stay on topic:
<read up a big-muff pi circuit, with your assortment of funny transistors. then go thru and work out what voltages are wrong and causing the circuit to mis-function.>
It's obvious (at least to me..) my city-mate Κωνσταντίνος isn't familiar with "right/wrong" voltages.. 
(in the mean of voltages ought to appear in case of item value/type change..)