GENERATOR- YOU DO THE IN/OUT POWER MATH

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I can't buy any more goodies until next week, but in the meantime i've had an idea that i'm going to try with what i have in my little plastic box.

1. Remove the magnet from the setup entirely.

2. Place the drive coil inside the induction coil. The drive coil has a ferrite core.

3. Pulse the drive coil with a signal generator.

Advantages :

No axle friction.
Probably less power input.
Quiet, so no moaning girlfriends ;+}
The drive coil can be pulsed much more rapidly than the magnet can rotate, effectively increasing RPM by a large amount.

Disadvantages :

A weaker magnetic field than the rotating Neo magnet.

That's the only disadvantage i can think of.

I want to make this circuit :

http://www.rmcybernetics.com/projects/DIY_Devices/homemade_signal_generator.htm

I have all i need, the cap i'm using is 10u, so i get 48Hz.

I have some questions, though. I'm still nervous when making circuits.

This is what i'm assuming from the circuit diagram (which is looking at the 555 from the underside mounted in a 14-pin IC socket), starting at the cap and going CW.

1. The cap goes from pin1 to pin2.
2. A 1k resistor from pin2 to the 10k pot.
3. The 10k pot goes to pin7.
4. The other 10k pot goes to a 1k resistor.
5. The resistor then goes to pin7.
6. Pins 6 and 2 are connected with wire.
7. A 100 o resistor from pin3 to output.

Also, i'm assuming the resistors go to the middle-leg of the pots.

Phew !

If anyone can help me with this i'd be very grateful


Gary.

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Hurray !!!

I figured it out

Perseverance is a wonderful thing !


Gary.

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Any ideas on how to add a 2N3055 to this so i can pulse a coil ?


Thanks,

Gary.

[gyulasun]

Hello Gary,

There is the series 100 Ohm resistor at pin 3 as the output, change this resistor to any value between 2.2 to 3.6 kOhm and this resitor would go directly from pin 3 to the 2N3055 base electrode. The emitter would go to negative GND and the collector would connect to one end of your coil and the coil's other end would connect to the positive supply voltage like 6V to 9V or 12V. 

You have to consider your coil's DC resistance when choosing your supply voltage from 6V to 12V because if you happen to have a 1 Ohm DC resistance coil and you happen to use 12V supply voltage then the collector current is nearly 12 Amper (from Ohm's law I=V/R) which is surely unnecessarily high for your application (unless you deliberately needs it).

Another problem might be the 70-80V absolute maximum collector emitter breakdown voltage for this transistor because a coil with relatively high inductance can produce rather high voltage spikes when the current is switched off in it, and you do not wish to burn out the transistor. A neon bulb like NE2 or similar can help to limit this high pulse to 60-70V if connected between the collector and emitter.  However, if you want to use this voltage spike and capture it in a capacitor via a fast switching diode then the neon is a drawback to use but then you have to choose another type of transistor that is able to withstand higher voltages like 250-300V or so.

Gyula

PS: by the way your previous questions were all with yes answers, as you figured out which is the best way of learning. 

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Thanks Gyula

Yes i really had to push myself on the sig-gen as it's only the second circuit i have built, i was very pleased when it worked. I had to attach a little speaker i took from a wind-up radio to the circuit then i heard it pulsing and heard the pulse change when i turned the pots.

So gratifying when you persever and it works !

Unfortunately i don't have and can't make up a 2.2k resistor or resistor-chain.

Could i use the ones from the circuit and replace those with two others ?

I'm not even sure what aspect of the signal those resistors affect, i think it's the duty-cycle ?


Gary.