Today I built the Taktile from Synth DIY Guy’s YouTube clip. https://youtu.be/DT6nZsixP0M
Great fun, especially if you lick it
Out of interest, it took a couple of hours for the copper the etch away in the ferric chloride solution I mixed. Is that normal?
It was ages since I used ferric chloride, but it sounds a bit high. But etching time depends on temperature and you also need to agitate the container now and then to make sure the surface is exposed to fresh etchant.
Thanks.
Agitating did help - and the solution was cold.
This was my second go at etching. First time I didn’t leave it in the ferric chloride long enough - I just thought the board underneath the copper was a pale pink colour.
That led to some head sctratching with the multimeter!
Did you brush up the copper before etching? It usually works better if it’s not oxidized.
No, I only gave it a good wipe with isopropyl alcohol to clean the surface before drawing on the two tracks with a Sharpie.
Next time I’ll try buffing the copper with some wirewool first.
and you get an additional prickly taste, unless you wash the board after etching …
To warm up the etching solution I once used an electric iron held upside down by a vice. I put a glass tray with the etching fluid on top of it. The power to the iron I reduced using a dimmer circuit for a light bulb. The fluid got warm but not hot in this way. Worked like a charm!
An old iron upside-down in a wise si great too. Has integrated “dimmer”.
After I’d finished the ironing I drew up the layout
I added an on/off switch to save the batteries and put a red led under the etched PCB for an eerie glow.
If I did it again I’d use a smaller resistor before the led to make it brighter.
I just found this nifty AA to 12v battery adaptor.
Anybody see any issues using this to replace the 9v battery?
Thought wtf and tried it anyway. Works a treat with 12v.
And the weight of the AA batteries adds a nice bit of heft to the case.
Is there a reason the PCB’s connected to the LED and not to the battery?
How much resistance do you get across the PCB? If I lick two fingers and hold multimeter probes between them I get about 1 or 2 M.
If you get something like that, then with the pot turned all the way left, 2V drop across the LED, and a 100k load on the CV, I’d expect the CV to go from ~0V to about 2((100k||10k)/((100k||10k)+1M)) ~ 0.018V. Very small.
But if the PCB connected to the other end of the resistor you’d get (with 12V battery) about 6 times higher CV, 0.11 V.
Still pretty small. Using a 100k pot would increase that.
Or am I for some reason seriously overestimating the PCB resistance?
Gee, that’s a bit to consider.
I only wired the led the way I did because it seems to work - and I am totally bluffing my way so thanks for the hints. Any improvements and suggestions are much appreciated.
I’ll have a chance to do some probing with a multimeter in a day or so and will try connecting the resistor to the other side of the board.
There was no switch or led in Synth DIY Guy’s example vid. I just knew that I would forget to disconnect the battery without them.
Board to the other side of the resistor, rather — the suggestion is that the board connect direct to the battery (or rather to the switch connected to the battery). Just move that one wire, red in your diagram.
