Caclulating a useable clock speed for RG's sequencer?

[bobbletrox]

I perfed up the pcb layout I posted for the "Stepping Stone" effect to make sure it actually works as stated, and it works fine:

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=27161

However, one thing that's been nagging me ever since I started fooling with R.G.'s sequencer is the range of the clock speed.  The 2.2uF cap that I've listed for C4 in the schematic actually makes the clock go way too slow to be useable, so I tried a 10uF, which has yeilded a good range from slow to fast, but now another problem has presented itself...

The speed control (a 500k trimmer in my case) doesn't gradually speed up throughout it's range - it seems to speed up exponentially with the final third of the range going straight from medium to uber-fast all of a sudden.  What sort of adjustment do I need to make to get the rate to change equally throughout the entire range of the pot?  I'm stumped!  If I were using real pots, they'd all be linear except for the volume pot, right?

One final quandry;
Obviously LEDs to indicate the progression of the sequence would be great, but it's not possible to tack a 2n3904/LED setup onto the sequence pots like the Vanishing Point has with this particular sequencer, is it?  What about a blinking LED for the clock speed instead?

Thanks for any help.

[The Tone God]

I perfed up the pcb layout I posted for the "Stepping Stone" effect to make sure it actually works as stated, and it works fine:

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=27161

However, one thing that's been nagging me ever since I started fooling with R.G.'s sequencer is the range of the clock speed.  The 2.2uF cap that I've listed for C4 in the schematic actually makes the clock go way too slow to be useable, so I tried a 10uF, which has yeilded a good range from slow to fast, but now another problem has presented itself...

Wow can't wait to see it.

The speed control (a 500k trimmer in my case) doesn't gradually speed up throughout it's range - it seems to speed up exponentially with the final third of the range going straight from medium to uber-fast all of a sudden.  What sort of adjustment do I need to make to get the rate to change equally throughout the entire range of the pot?  I'm stumped!  If I were using real pots, they'd all be linear except for the volume pot, right?

I found that 10uF and 100K liner pot with a 1K series speed limiting resistor pretty good. Thats just me though.

One final quandry;
Obviously LEDs to indicate the progression of the sequence would be great, but it's not possible to tack a 2n3904/LED setup onto the sequence pots like the Vanishing Point has with this particular sequencer, is it?  What about a blinking LED for the clock speed instead?

Not in a simple way since the stage selection is being decoded. I think the best way if you really want to to have an LED for each stage is to slap in another 4051 in, decode off the same lines from the 40193, and switch the LEDs off the second 4051's outputs.

As for a speed LED if you have a spare inverter gate from the 40106 then stick your clock signal through that using the gate as a buffer and drive an LED with it.

Andrew

[bobbletrox]

Thanks andrew!  I'll have to go pick up the parts to try those out tomorrow.  Hopefully those values will sort the clock out.  I'll also have to buy a pile of LEDs to try hooking them up to a second 4051 for the sequence indicators.  The addition of an extra IC will make the size of the PCB bigger, but you've gotta have some way of monitoring the sequence I reckon.

As for the blinking clock speed LED, did you mean connect the clock output (bright pink pin) to the input of an inverter (pin 3) and then its output (pin 4) directly to an LED to ground?  I tried it out but the LED just stayed lit.

I think I posted the final schematic a bit prematurely because although there aren't any show-stopping bugs, there are still a few values that need tweaking.  I double checked RG's original sequencer diagram and noticed that the output of the sequencer (C7 on my diagram) is supposed to be a 10uF np cap, whereas I've used a regular 100uF electro for some reason.

[The Tone God]

Thanks andrew!  I'll have to go pick up the parts to try those out tomorrow.  Hopefully those values will sort the clock out.  I'll also have to buy a pile of LEDs to try hooking them up to a second 4051 for the sequence indicators.  The addition of an extra IC will make the size of the PCB bigger, but you've gotta have some way of monitoring the sequence I reckon.

I agree. Thats why with the new Vanishing Point I inculded that. Especially with so many stages you want to know what knob to tweak.

As for the blinking clock speed LED, did you mean connect the clock output (bright pink pin) to the input of an inverter (pin 3) and then its output (pin 4) directly to an LED to ground?  I tried it out but the LED just stayed lit.

If I read your schematic correctly then your clock's output is on pin 6. You should be able to throw that straight into pin 3 with the LED output on pin 4. If not try picking up the clock from pin 2 (purple dot). That should work.

I think I posted the final schematic a bit prematurely because although there aren't any show-stopping bugs, there are still a few values that need tweaking.  I double checked RG's original sequencer diagram and noticed that the output of the sequencer (C7 on my diagram) is supposed to be a 10uF np cap, whereas I've used a regular 100uF electro for some reason.

You should change that cap. I wouldn't be surprised if its affecting your speed control especially on higher speeds.

Good luck.

Andrew

[bobbletrox]

If I read your schematic correctly then your clock's output is on pin 6. You should be able to throw that straight into pin 3 with the LED output on pin 4. If not try picking up the clock from pin 2 (purple dot). That should work.

Ahh...pin 2 did the trick.  I'll also try out the 8 seperate LEDs and change that 100uf cap to a 10uF np.

http://users.bigpond.net.au/styrowfoam/steppingstone.pcb

I've also realised that there's some clicking in the audio from the clock in the layout I made (above), so I guess the decoupling cap across the rails need be larger for starters.  Of course, it doesn't help that the clock is right next to the power section and the wire from the clock to the sequencer passes right over the audio section.  Doh!

My original perf of this effect had the sequencer and PWM on different boards so there was no clicking - but in this version they're jammed up next to each other so they can use the same Schmitt IC.

[bobbletrox]

Thanks for your help Andrew.  The clock's got a good range now and I got the sequence indicator LEDs up and running by using the 4051 as a switch to ground each LED.  

I've decided that it's no good having the PWM circuit and sequencer combined in the same layout because there's too much clicking.  Would having them on seperate boards with their own power filters solve it?

Here's a diagram of how the lone-sequencer with LED indicators:

http://users.bigpond.net.au/styrowfoam/sequencer-leds.gif

Oh yeah...and this may sound kooky, but playing harder seems to make the sequencer go faster!

[The Tone God]

Great to hear you got things going.

I've decided that it's no good having the PWM circuit and sequencer combined in the same layout because there's too much clicking.  Would having them on seperate boards with their own power filters solve it?

Ah the age old question of getting rid of clock ticking. Yes seperating circuits and isolating the power supplies can help but that may not solve the problem completely. There are a number of things you can do to reduce noise. Some include:

- Isolate power supplies.

- Physically seperate the audio from the logic.

- Keep wire runs away from each section.

- Use sheilded wire for any wire runs that come near other sections.

- Use seperate grounds for logic and audio connecting each sections's ground at one point only.

That last one is a biggie that many overlook.

Oh yeah...and this may sound kooky, but playing harder seems to make the sequencer go faster!

It sounds like the pull of your audio section on the power supply is causing instabilty in the timing circuitry. I haven't built this circuit so I don't know how it behaves and can't offer any solid answers. I've only built the Vainishing Points and know that I resolved most of these problems with it. Sorry.

Andrew

[bobbletrox]

You know what?  After checking out the Original Vanishing Point, I've decided to ditch my ever growing behemoth.  I could wire up the original Vanishing Point's 4066 so it's doing the exact same thing as the 4051 in my current setup.  However, this time I'll place the PWM's power supply and the bias network for the sequence pots away from the sequcencer's ground and power supply.

I'm no electronics brainiac, but can't capacitor arrays be used to improve power filtering, kinda like this?  

[The Tone God]

You know what?  After checking out the Original Vanishing Point, I've decided to ditch my ever growing behemoth.  I could wire up the original Vanishing Point's 4066 so it's doing the exact same thing as the 4051 in my current setup.  However, this time I'll place the PWM's power supply and the bias network for the sequence pots away from the sequcencer's ground and power supply.

You won't be able to directly replace the 4051 with two 4066s. The 4051 decodes the output of the 40193. The 4066s just responds to binary input and cannot decode anything. Note that I'm using a 40194 in The Original Vanishing Point not a 40193. You would need to either decode the output of the 40193 or use the 4051 to control the two 4066s adding yet more circuitry in either case.

Not to toot my own horn but to be honest I think the new Vanishing Point is much better, easier, smaller, and cleaner then other solutions including The Original Vanishing Point. The only really tough part is getting optocouplers to fit the situation. I was even thinking of doing a PCB for the 40106 instead of the 4093 since I have had a few inquires about that.

I'm no electronics brainiac, but can't capacitor arrays be used to improve power filtering, kinda like this?

They can but alot of times you don't need that much and those won't nesscarily solve a problem that is coming from the inside. A fairly simple and generally effective way of isolating supplies is to put a 100ohm resistor in series with the supply and a cap to ground after that.

Andrew