Timmy Update Verification

[Rob Strand]

Re the schematic and my previous comments:
- The units with the 18k resistor (which is what the schematic applies to)
   always seem to use the RF cap and always use JRC4559D opamps.
- It's a bit fuzzy but from July 2013  the 18k might have been solder to the pot
- Then later on, say Jan 2014, the PCB was changed to incorporate the 18k.
- By July 2013 I'm pretty sure the LM1458N was removed from production.
  The LM1458N was only used units without the traditional purple color.
  So apart from a fuzzy region around July 2013 the V2 schematic never had LM1458N's

I've put together a Timmy *V2* "This is your life" document.
(It's attached to the post but you have to be logged in to get it.)
It's the best I can do with the info I have.
I don't think I will add to it.  I'm sure it has some errors.
Use the manticorefx effects site link for pics.  However I'm pretty sure it doesn't cover all the cases.

The version numbers in the doc are mine.  It's the only way I could keep track of them.

[Elijah-Baley]

Thanks! I love these kind of work.

[bloxstompboxes]

Re the schematic and my previous comments:
- The units with the 18k resistor (which is what the schematic applies to)
   always seem to use the RF cap and always use JRC4559D opamps.
- It's a bit fuzzy but from July 2013  the 18k might have been solder to the pot
- Then later on, say Jan 2014, the PCB was changed to incorporate the 18k.
- By July 2013 I'm pretty sure the LM1458N was removed from production.
  The LM1458N was only used units without the traditional purple color.
  So apart from a fuzzy region around July 2013 the V2 schematic never had LM1458N's

I've put together a Timmy *V2* "This is your life" document.
(It's attached to the post but you have to be logged in to get it.)
It's the best I can do with the info I have.
I don't think I will add to it.  I'm sure it has some errors.
Use the manticorefx effects site link for pics.  However I'm pretty sure it doesn't cover all the cases.

The version number in the doc are mine.  It's the only way I could keep track of them.

Lol. There are some who call me... Tim.

[Rob Strand]

Lol. There are some who call me... Tim.

Indeed.
"What manner of man are you, that can summon fire without flint or tinder?"

PaulC said that's where he got the name for the Tim pedal, which later evolved into the Timmy pedal.

[Rob Strand]

Thanks! I love these kind of work.

It takes a lot of time.   I promised myself I'd stop doing that type of stuff 

[Elijah-Baley]

I'm comparing the veroboard layout in tagboard guitar fx web site



with the schematic you guys drawn because I want to update it.

First of all the easier mod to update.
- Replace the 1.5k with a 1k.
- Replace the two 3.3k resistors to the right side with two 10k
- Replace the 47nF cap with a 39nF

- Add the 2.2nF
We can do it, even if the position is a bit unhandy. This cap has to be in parallel with pin 6 and pin 7 of the IC.
We have to use two holes, one under the 1uF cap (the bigger, near the 47uF cap) on the same stripe of the pin 6, and the other hole is to the right of the 1uF between it and the 3.3k resisitor, on the same stripe of the pin 7.

Now a thing I need some help.
- Add C4, the 47pf cap in the new schematic.
I still didn't understand what happens in these cases. It's hard for me explain this and I tried to write it a lot of time, but to be brief... How much important has the position of the 47pF? Can I put it simply in parallel between the pin 3 (the signal) and the pin 4 (the ground) of the IC without take care if it's before or after the C3, R3 and R4?
Because there's a place, two holes, between the two wires Drive 3 and Input. Could it ok?

Then there's some difference in the power filter. The schematic has a protection diode (D1) on the ground, while the veroboard layout has the diode and a 100R resistor along the 9v. I think we have enough room to make some changes. Anyway, I don't know how much it could make some difference in the sound.

I have a doubt about the number of the clipping diodes. Why in the layout there are seven diodes and in the schematic there are five? Did I miss something?

[Rob Strand]

First of all the easier mod to update.
...  1uF between it and the 3.3k resisitor, on the same stripe of the pin 7.

All that looks OK to me.

Can I put it simply in parallel between the pin 3 (the signal) and the pin 4 (the ground) of the IC without take care if it's before or after the C3, R3 and R4?
...
Could it ok?

Across pin 3 and pin 4 is correct.  It matches the new schematic.  (It also matches what I can see on the pics of the actual PCB.)

Then there's some difference in the power filter. The schematic has a protection diode (D1) on the ground, while the veroboard layout has the diode and a 100R resistor along the 9v. I think we have enough room to make some changes. Anyway, I don't know how much it could make some difference in the sound.

You did well to find those small details.   The protection on that layout does not match Timmy V1.0 or Timmy V2.0.   Both Timmy V1.0 and Timmy V2.0 do not use the 100R and the diode is not in series with the power.  The actual circuit connects the diode in a completely different way.  You need to connect it across pin 4 and pin 8, as shown in the new schematic.

As for the difference in sound it will be small.  If you leave the layout as shown it will be like running the real Timmy circuit with a slightly flat battery.   I am in two minds about updating the layout.  I read that PaulC changed the 3.3k's to 10k's in order to gain a small amount of extra headroom from the opamp.   With the layout as shown it is actually throwing away headroom because of the voltage drop of the diode and the 100R resistor.   So if you just want something that sounds very close leave the layout as is.  However if you want a true clone which goes along with PaulC's intentions then you should change it.

I have a doubt about the number of the clipping diodes. Why in the layout there are seven diodes and in the schematic there are five? Did I miss something?

The original Timmy 1.0 had six clipping diodes and a 2-way dip-switch.   That Timmy V1.0 layout is missing the diodes and the dip switch.   For Timmy V2.0  the circuit uses 5 diodes and a toggle switch.  The toggle switch is mounted on the front of the enclosure.   To make the layout a full Timmy V2.0 you will need to add the extra diode and also add some connections for the toggle switch.   The added parts are D6 and S1 on the schematic.

[Elijah-Baley]

Thanks to you for the help, Rob!

I'd say, to adjust the power section as the original Timmy, we can remove the 100R, take off for an instant D8 polarity protection diode, move the 9v just under the Vol 3 wire. The D8 can goes in parallel with the 47uF cap between the 9v and the ground, following the schametic. Maybe we could handle a bit the surface spacing, but in the end it will be ok, I think.

About the clipping, in this page https://www.diystompboxes.com/smfforum/index.php?topic=108272.msg986355#msg986355 I found this:



This explain me how the Timmy V1 with the internal switch worked: you can let disconnected the diodes, or you can add one diode (or the other one) or you can add both those two diodes. For a three way mode.
The external switch makes the same thing in a different way. You can exclude the extra diodes, or you can add one diode or you can add two diodes. And in this case we have one more diode, but the clipping modes are exactly the same.

But there's still something I can't get with the new connections of the diodes in the newer schematic.

I update the nocentelli sketch:



No, I can't follow the signal through these connections and these diodes.

[Rob Strand]

But there's still something I can't get with the new connections of the diodes in the newer schematic.

The first schematic is close to Timmy V1 but it isn't 100% correct.  The 4 diodes should have a connection between the top 2 diodes and the bottom 2 diodes.  I remember reading that PaulC said "it makes a difference".

The second schematic is close to Timmy V2 but it isn't 100% correct.  It creates a circuit which functions like Timmy V2 but does so by starting with Timmy V1 then changes the dip-sw to a toggle switch.

The third schematic is how the Timmy V2 is wired on the PCB.   Timmy V2 only as 5 diodes so it cannot use the method of the second circuit which has 7 diodes.   (Timmy V1 has 6 clipping diodes.)

IMHO, the second schematic and third schematic will sound virtually identical.   For the 2 diode mode (compressed), the clipping action of the second circuit comes from the lower 2 diodes and the upper 4 diodes do not conduct.   For the third circuit the clipping action comes from the right 2 diodes and the left 2 diodes are out of circuit.

[EDIT: Maybe one thing that might be confusing.  When the two diodes are switch in on the second circuit they limit the voltage to +/-0.6V.   This prevents the top four diodes from conducting.  The four diodes don't conduct until the voltage reaches +/-1.2V but the two diodes stops it getting there.  So it is like the four diodes are switched out.]

[Elijah-Baley]

Thanks again, man!
The last thing you added was told to me some years ago by duck_arse. I never really really get it. Maybe this time I got it.

Anyway, while I was staring the third schematic it was like a little lamp that turned on in my mind, and I guess I finally got something! But not completely.

I'm very sorry if I insist, but there's really something that confuse me in the cross of connection in the third schematic, and maybe in the notes on the schematic drawn early by you:

"Clipping Switch S1:
1-2: Asymmetrical 1|2 diodes
Off (center): Symmetrical 2|2 diodes
2-3: Symmetrical 1/1 diodes"

The thing I don't get is how exactly the signal pass through the all the diodes in this three modes.
When S1 connects 2 to 3 I get that D2 and D5 are bypassed because the switch has create a parallel connection. So we have D3 and D4 in parallel, D2, D5 and D6 are out, so just two diodes. I used to write this like so: 1||1, and maybe we are ok.
When S1 connects 2 to nothing we still have D6 out, but we have four diodes where series and parallel confuse me. That vertical link between the four diodes is driving me crazy. What is happening? We really have two pair of diodes in parallel? Like this 2||2?
When S1 connects 2 to 1, of course, happens the same thing when S1 connects 2 to nothing plus D6. But how we can get 1||2? I mean one less diode?

If there's somebody with a lot of patience that can help me, please.

Thanks to all!

[Rob Strand]

1|2

Don't get stuck on the "|" or "||"  it's only a short hand of writing down the configuration in *"words"*.  In the end the circuit diagram represents how it is connected.

D2, D5 and D6 are out, so just two diodes.

That's correct.

When S1 connects 2 to nothing we still have D6 out, but we have four diodes where series and parallel confuse me. That vertical link between the four diodes is driving me crazy. What is happening? We really have two pair of diodes in parallel? Like this 2||2?

When you have the extra link it's more like 1||1 in series with another 1||1.  When you take the link out it's 2||2.   The simple way to think about it is the diodes can only conduct in the positive direction so if current flows left to right D2 & D3 conduct and D4 & D5 are off.  When current flows from right to left  D4 & D5 conduct and D2 & D3 are off.   If you think this way you should see that the circuits do the same thing with the link in or the link out.   You might ask what's the difference, why bother?  PaulC said it makes a difference to him.  If the diodes are all the same I'm not sure I can explain *why*.

When S1 connects 2 to 1, of course, happens the same thing when S1 connects 2 to nothing plus D6. But how we can get 1||2? I mean one less diode?

If you understand the note at the end of my last post about 0.6V and 1.2V you should get this.  So in one direction you have D4 and D5 clipping just like the case with four diodes.  However when the current is reversed.  D6 which is 0.6V is connected in parallel with D2 + D3 which is 1.2V  so D6 makes D2+D3 look like they are out of circuit.  So it's like 4 diode case in one direction and the 2 diode case in the other direction.

[GGBB]

Rob beat me to it, but reading another explanation might help.

When S1 connects 2 to nothing we still have D6 out, but we have four diodes where series and parallel confuse me. That vertical link between the four diodes is driving me crazy. What is happening? We really have two pair of diodes in parallel? Like this 2||2?

Current can only flow in a diode's forward direction (assuming the voltage is lower than the diode's reverse breakdown voltage). Trace current flow and see how many paths you can make through diodes between pins 1 and 2 (paths that end up back where they started don't count). There are only two paths - one in either direction. From pin 1 through D4 and D5 to pin 2, and from pin 2 through D2 and D3 to pin1. The center connection of all four diodes is distracting but it actually does nothing, other than enable the clever clipping switch arrangement.

When S1 connects 2 to 1, of course, happens the same thing when S1 connects 2 to nothing plus D6. But how we can get 1||2? I mean one less diode?

It is not "nothing plus D6." D6 is in parallel with the D2-D3 series, but because a single diode has half the forward voltage of two diodes, current flows through D6 only. (I think this is a simplification - it may actually be more complicated but the net result for soft clipping is the equivalent of one diode in operation.) The D4-D5 series still operates in the other direction.

[Elijah-Baley]

Great! It's more clear, now!

So, with the corrections of the Timmy's schematic I'm wondering what about the Jan Ray, too. Everybody consider it how a clone of the Timmy with some mods. And the clipping section? The Jan Ray has the four diodes, but without that link. Who knows if it is really like that or this mistake of the missing link has been transferred to it.

[Rob Strand]

So, with the corrections of the Timmy's schematic I'm wondering what about the Jan Ray, too.

Before I started this thread I had many circuits and layouts of "Timmy".  All different!   I had no idea what was real, what was bad tracings, what was a DIY version.  A big mess!   It's a relatively simple circuit so how can things get so out of hand!  It happens *all the time* many simple circuits suffer the same problem.

The main problem is people put up schematics that they know aren't 100% but they make it out like it *is* the real thing.   Once that happens the error propagates all over the place.  When I don't know something I try to write it on the schematic.  At least then someone only has to check *that* small part.   Some people don't have the skill to trace the whole circuit but if they only have to check a small section they can usually do it.

Wrong pot tapers, or no pot tapers happens is another one.  If DIYers don't like the pot taper they change it on the schematic to what they have used but they don't add any notes.

Just look at the Klon.   There were *many* different schematics on the Web and one guy set out to finally get it right.   It took a couple of attempts (which is normal) but he finally got there.

Everybody consider it how a clone of the Timmy with some mods. And the clipping section? The Jan Ray has the four diodes, but without that link. Who knows if it is really like that or this mistake of the missing link has been transferred to it.

If you look at the Jan Ray it has many circuit differences, yep, including the diodes.  So it's not really a Timmy.

When I researched the Timmy I found a post from PaulC saying if you are going to put up a schematic of Timmy, call it Timmy! don't call it something else.  He even corrected people's incorrect schematics and helped with missing values.  I remember him saying that the 4 diodes have the connection between them!!! and "it makes a difference".

FYI, IMHO even Timmy V1 circuit isn't quite correct:
- IC's have wrong (or no) pin numbers
- Bass and treble pots don't connect pin 3
- Pretty sure the dip-sw connects to the opamp output, not the opamp input.
- When you look at the Timmy V1 PCB or Vero layouts there's a 3k3 resistor missing.
  I think the 3k3 is wired to the back of the Gain pot.
- There's not enough wires to connect all the pots so I think at the opamp output
  there's only one wire and the Gain and Treble pots are connected with together off the PCB
  then one wire runs back to the PCB.

So many details that are possibly wrong and the circuit only has one IC!

[GGBB]

EDIT: Never mind - momentary lapse of sanity. 

[Elijah-Baley]

Hi, guys!
I'm still working with the new layout of Timmy. I was a bit busy. There just a thing I have to say.
Looking at the layout, posted above: https://www.diystompboxes.com/smfforum/index.php?topic=121481.msg1142928#msg1142928 I noticed that the diodes, after all we talked about the connections, etc., they are connected in the correct way, like the last update schematic. If it is so I will not move anything, except the clipping switch that we need to update, and it is a bit hard to got it clean as possible. Probably we should have a flying diode, we'll see.

[segoy]

I'm still waiting for the final layout 

[Elijah-Baley]

You're right. I made and forgot it!
Anyway, I just modified the old layout you can find on tagboard web site. Tha main difference are in some value.
Input cap: from 47nF to 39nF
Resistor cap: from 1.5k to 1k
Feedback resistors in the second stage: the two 3.3k are now 10k
Add a 47p from input to ground, you can find a place on the left of the board
Volume pot: from 10k log to a 25k log with a 18k between lug 2 and 3.

And the some minor changing in the power supply. The new schematic shows not a diode in line to the 9v, but one across the ground. A 1N4001 will be fine.

Now, looking my layout again, I'm not sure is really ok, I just some doubt about the clipping mode. I remember I had some doubt in the past. I'll look at it, again.

[segoy]

Thank you!
I think I'll try to build the "new" Timmy and these values.
Yes, you had some doubts about clipping - if you find out something, please drop some info

cheers!

[duck_arse]

....... Probably we should have a flying diode, we'll see.

all flights cancelled, all diodes grounded.