Hi all,
Im a new-ish electronics hobbyist -can anyone give me advice on a project?
I want to power a sheet of electrochromic film with electricity generated from a bicycle. It’s part of a live game so I need the cycling to last between one and two minutes.
I could use a dynamo which will have a dc output, and an inverter (because the smart film requires 60vac. Or I thought I could use mains power to a transformer to a 12v relay and have a dynamo switch the relay.
What I don’t know is how to make it so that pedalling is required for two minutes. I want the electrochromic film to only be powered whilst peddling but I don’t want the reaction to be instant.
Am I going about this the wrong way?
Any advice appreciated.
Tom

 

To clarify - you want the person to pedal for two minutes while keeping the film off, then apply power at the two minute mark and keep power applied until pedaling stops - ?

If so, not difficult. What are your circuit wiring skills, or would you rather use pre-assembled modules from ebay?

ak

 

Yeah I think so (might be one minute- I’d need to test it out on people).
Should I go down the time delayed relay route?
I’m ok at wiring and soldering but don’t have much circuitry knowledge (I.e. I could follow a diagram to build a circuit board but probably couldn’t design one and know what everything did and why I needed it.)

 

These may not be the final circuit functions, but the operational functions are:

1. Detect start of pedaling.
2. Wait for one continuous minute of pedaling.
3. Switch power on.
4. Detect stop of pedaling.
5. Switch power off.
6. Goto 1.

Yes?

ak

 

Yes that would be the functions.
Tn

 

What are you options for a rotation sensor? Do you need the dynamo to actually power something, or is it acting only as a rotation sensor? Do you have other options to detect pedaling?

A circuit that can do this is two retriggerable monostable multivibrators, or retriggerable one-shots, basically a resistor-capacitor timer and a threshold detector. The first one makes a signal as long as the pedals are moving, and the second one monitors the first one for the one minute delay period, and is reset if pedaling stops (signaled by the first one). If it is allowed to run its full time period, it turns on the output. Then, when pedaling stops it is reset again and turns off the output. This can be done with two 555's, or one CMOS gates like a CD4093, or some of transistors.

You get a "free" pedaling indicator if the dynamo powers the circuit; then it's just the one minute timer with a power-on reset.

So what is the overall power plan? Dynamo power's everything, AC power for the load but the dynamo powers the timer, 12 Vdc power for the timer, other?

Where are you located?

ak