Where have you been?
The last 3 or 4 years I have been studying electronics with the aim of making a synthesiser. I'll use this blog to document this and to maybe help others along the way
Electronics DIY stuff
Make Electronics Experiment 18: Reaction Timer
For anyone attempting this, I'd advise reading the errata on the website first: don't connect pins 4 & 5 of the 4026's to ground and swap the R10 1k resistors for for 10k. The 1uF capacitor should be 0.1uF etc. Also, to get mine to reliably work I had to remove the the positive pin connection on IC1 pin 16.
For anyone attempting this, I'd advise reading the errata on the website first: don't connect pins 4 & 5 of the 4026's to ground and swap the R10 1k resistors for for 10k. The 1uF capacitor should be 0.1uF etc. Also, to get mine to reliably work I had to remove the the positive pin connection on IC1 pin 16.