TC SPARK BOOSTER MINI [schematic]

[rcustoms]

Hi!
I'd like to ask you, is this schematic the same of the original TC Electronic? And is it verified?

I also want to link this layout:
http://effectslayouts.blogspot.it/2017/ ... -mini.html
It's labeled as UNverified, but should be verified by an user, though the Gain pot could be reversed. This layout use the 500k gain pot, so it included the 100pF cap.

I need a verified version.

Thanks!

hi,values verified ,oops my mistake gain pot 100k ,and interprete as you wish the right position

[rcustoms]

original gain schema

[Ichabod_Crane]

Thank you.
1. In the schematic there's a cap labeled C2 - 4.7k, I guess it's a 4.7uF.
2. Between the protoboard layout and the schematic I found different transistors, because the BC849c and BC859C are probably smd type.
3. The the diode should be for the reverse polarity protection: in the schematic it's in serie and in the layout it's across the ground.
4. In the layout the 100nF filter cap is missing. Maybe with a pair of move we van find the space to include it.

I see who built the layout had find an "output overload". Maybe it was caused by the 500k pot? Now we know it's 100k.

[rcustoms]

Thank you.
1. In the schematic there's a cap labeled C2 - 4.7k, I guess it's a 4.7uF.
2. Between the protoboard layout and the schematic I found different transistors, because the BC849c and BC859C are probably smd type.
3. The the diode should be for the reverse polarity protection: in the schematic it's in serie and in the layout it's across the ground.
4. In the layout the 100nF filter cap is missing. Maybe with a pair of move we van find the space to include it.

I see who built the layout had find an "output overload". Maybe it was caused by the 500k pot? Now we know it's 100k.

I, mr ichabot

1. yes is 4.7uf
2.the right one´s BC849C
3.the diode correct is in serie
4.which layout,mine ?

[Jan1966]

Build it or breadboard it. Then verify it yourself. Not many components if you are worried about the cost.

[Ichabod_Crane]

[...]
3.the diode correct is in serie
4.which layout,mine ?
[...]

3. I thought that a diode in serie and a diode across the ground do the same work. I also supposed that in serie, the diode, drops a bit of voltage (even if in this case we already have a 47R in serie). Anyway, these two way can have make some difference?
4. And, I'm sorry , I was talking about the layout I linked early: http://effectslayouts.blogspot.it/2017/ ... -mini.html You can see the 500k pot, how I asked, can be that the cause of the extra boosting detected? I'm not sure, I can't get it.

Did you build your layout?

Build it or breadboard it. Then verify it yourself. Not many components if you are worried about the cost.

Thank you, Jan1966. Honestly, the pedal wouldn't be for me, but for a friend of mine, and though I know the cost are not high at all, I'll never make to pay my friend, and at the same time I don't know if want to spend for me, right now. I have a cheap breadboard, but even cheapers jumpers, and I'm not very confortable with it. But, maybe I could use it heavily this time and see what happen.

[rcustoms]

[...]
3.the diode correct is in serie
4.which layout,mine ?
[...]

3. I thought that a diode in serie and a diode across the ground do the same work. I also supposed that in serie, the diode, drops a bit of voltage (even if in this case we already have a 47R in serie). Anyway, these two way can have make some difference?
4. And, I'm sorry , I was talking about the layout I linked early: http://effectslayouts.blogspot.it/2017/ ... -mini.html You can see the 500k pot, how I asked, can be that the cause of the extra boosting detected? I'm not sure, I can't get it.

Did you build your layout?

Build it or breadboard it. Then verify it yourself. Not many components if you are worried about the cost.

Thank you, Jan1966. Honestly, the pedal wouldn't be for me, but for a friend of mine, and though I know the cost are not high at all, I'll never make to pay my friend, and at the same time I don't know if want to spend for me, right now. I have a cheap breadboard, but even cheapers jumpers, and I'm not very confortable with it. But, maybe I could use it heavily this time and see what happen.

i don´t make it yet soom as posible.
3.the diode in the original schem is in series ,just for info

[Gillesmerlin]

I have a trouble with this board. It seems that the pot is not working, that it is always at max !
Can someone help me ?

[Reachahighernoon]

Can someone explain to me, please, why is this circuit so overbuilt?

[grrrunge]

Can someone explain to me, please, why is this circuit so overbuilt?

Well. Essentially, it isn't. If it's simplicity you're after, you have the one transistor designs: SHO, LPB1 etc. If it's transparency and linearity, there's the op amp based ones like the micro amp.
This one is essentially in the latter category, but to save production costs, the op amp is built with just a few transistors. They've most likely saved 10 cents on the BOM cost that way. If you put out 100.000 pedals, that's a big saving right there

[Reachahighernoon]

Can someone explain to me, please, why is this circuit so overbuilt?

Well. Essentially, it isn't. If it's simplicity you're after, you have the one transistor designs: SHO, LPB1 etc. If it's transparency and linearity, there's the op amp based ones like the micro amp.
This one is essentially in the latter category, but to save production costs, the op amp is built with just a few transistors. They've most likely saved 10 cents on the BOM cost that way. If you put out 100.000 pedals, that's a big saving right there

Oh! So it's a discreate opamp design!? Like the Boss Blues Driver?

[grrrunge]

Can someone explain to me, please, why is this circuit so overbuilt?

Well. Essentially, it isn't. If it's simplicity you're after, you have the one transistor designs: SHO, LPB1 etc. If it's transparency and linearity, there's the op amp based ones like the micro amp.
This one is essentially in the latter category, but to save production costs, the op amp is built with just a few transistors. They've most likely saved 10 cents on the BOM cost that way. If you put out 100.000 pedals, that's a big saving right there

Oh! So it's a discreate opamp design!? Like the Boss Blues Driver?

Indeed so. The entire circuit is one discrete op-amp - fully class-a.

[Reachahighernoon]

Can someone explain to me, please, why is this circuit so overbuilt?

Well. Essentially, it isn't. If it's simplicity you're after, you have the one transistor designs: SHO, LPB1 etc. If it's transparency and linearity, there's the op amp based ones like the micro amp.
This one is essentially in the latter category, but to save production costs, the op amp is built with just a few transistors. They've most likely saved 10 cents on the BOM cost that way. If you put out 100.000 pedals, that's a big saving right there

Oh! So it's a discreate opamp design!? Like the Boss Blues Driver?

Indeed so. The entire circuit is one discrete op-amp - fully class-a.

So the only reason for this is cost saving?

[grrrunge]

Can someone explain to me, please, why is this circuit so overbuilt?

Well. Essentially, it isn't. If it's simplicity you're after, you have the one transistor designs: SHO, LPB1 etc. If it's transparency and linearity, there's the op amp based ones like the micro amp.
This one is essentially in the latter category, but to save production costs, the op amp is built with just a few transistors. They've most likely saved 10 cents on the BOM cost that way. If you put out 100.000 pedals, that's a big saving right there

Oh! So it's a discreate opamp design!? Like the Boss Blues Driver?

Indeed so. The entire circuit is one discrete op-amp - fully class-a.

So the only reason for this is cost saving?

The only practical reason as far as I see it. The fact that it can also be marketed as pure class-a ie. no crossover distortion etc. might also have something to say.

[Reachahighernoon]

The only practical reason as far as I see it. The fact that it can also be marketed as pure class-a ie. no crossover distortion etc. might also have something to say.

But cant you an opamp class A? I think I saw schems of that....

[grrrunge]

The only practical reason as far as I see it. The fact that it can also be marketed as pure class-a ie. no crossover distortion etc. might also have something to say.

But cant you an opamp class A? I think I saw schems of that....

Since all of the transistors are biased on all the time, this circuit is by textbook definition class-a all the way through.
There are integrated class-a op-amps available, but again; the cost saving of using 5 transistors instead of a somewhat exotic IC is significant.

[roseblood11]

Does this circuit need changes, if a symmetrical supply with two batteries ( +/- 9V) is used? Except for the obvious (remove voltage divider...)

[grrrunge]

Does this circuit need changes, if a symmetrical supply with two batteries ( +/- 9V) is used? Except for the obvious (remove voltage divider...)

- Tie R14, R8, R11 and emitter of T3 to the negative supply voltage instead of GND.
- Remove C5 and tie R10 directly to GND
Everything else stays the same. Enjoy your increased headroom

Alternatively you can just feed the circuit 18V. The end result is the same.
DC performance of this circuit is less than admirable. I wouldn't use it in DC coupled applications, if that's what You're after.

[roseblood11]

Except for the obvious

thx