Quick hall effect sensor + mosfet conversion to sg wheel

[bigmotherwhale]

decided to try out hall switching before my next build so i grabbed the junk box and pulled apart some fans and got the hall sensor out and connected them to a mosfet driving an SG bike wheel.
seems to work as i expected, needs an astable, pulse width is quite long, charging seems good but the battery is pretty dry and sulphated.

http://vid936.photobucket.com/albums...ps223c2aff.mp4

[Ed_Morbus]

Thanks for sharing

Have you schematic ?

[bigmotherwhale]

it needs a timer to change the pulse width, and an opto isolator if you are going to run higher than 12 - 14v

[bigmotherwhale]

circuit i will build next. one with resistors before holding pin 2 high is correct

[Ed_Morbus]

Thank you for your time

[Gary Hammond]

Hi BMW,

decided to try out hall switching before my next build so i grabbed the junk box and pulled apart some fans and got the hall sensor out and connected them to a mosfet driving an SG bike wheel.
seems to work as i expected, needs an astable, pulse width is quite long, charging seems good but the battery is pretty dry and sulphated.

I rigged mine up with two hall switches in series on separate adjustable mountings. This allows me to adjust both the timing and pulse width mechanically without using a 555 timer circuit. It seems to work best at about 20 percent on time. I use a small signal transistor in the base circuit of the 21194 power transistors.

[bigmotherwhale]

good idea, also using 21194 seems like a good plan, i will see how long my mosfets hold up.

[Brian McNece]

Any chance that some one could post the bedini SG schematic with a hall switch substituted for the trigger wire, I would like to see the difference but don't quite know how to do that.


[QUOTE=Gary Hammond;16842]Hi BMW,

decided to try out hall switching before my next build so i grabbed the junk box and pulled apart some fans and got the hall sensor out and connected them to a mosfet driving an SG bike wheel.
seems to work as i expected, needs an astable, pulse width is quite long, charging seems good but the battery is pretty dry and sulphated.

QUOTE]

I rigged mine up with two hall switches in series on separate adjustable mountings. This allows me to adjust both the timing and pulse width mechanically without using a 555 timer circuit. It seems to work best at about 20 percent on time. I use a small signal transistor in the base circuit of the 21194 power transistors.

[Gary Hammond]

Hi Brian,

Give me a few days and I can post a schematic of what I did. I'm currently away from home on a mini vacation and posting this from a motel room using my wife's laptop.

cheers,

[Brian McNece]

Thank you, hope you have a nice vac.

Hi Brian,

Give me a few days and I can post a schematic of what I did. I'm currently away from home on a mini vacation and posting this from a motel room using my wife's laptop.

cheers,

[bigmotherwhale]

the monostable circuit is useless, the input pulse duration affects the output pulse duration, back to the drawing board

[bigmotherwhale]

problem solved, mosfet isolation driver stage next.http://vid936.photobucket.com/albums...ps3cc1ee71.mp4

[bigmotherwhale]

sucess, variable pulse width and timing, mosfet driven simply from optocoupler but not yet ready for high voltages, it produces the biggest spikes, and i cant dampen them enough with a battery to stop the neon protection on the mosfet from staying on, without the battery the neon is not yellow but bright blue / white.
the wheel spins a reasonable speed with a very small duty cycle at around 200ma including the switching and i only have a single coil winding out of 8 connected (140ft x 0.5mm)

http://vid936.photobucket.com/albums...ps6a2fd9bd.mp4

[wrtner]

I always thought that one of the essential essences of the SG is that it does not need or want a Hall sensor. Am I wrong?

[bigmotherwhale]

I always thought that one of the essential essences of the SG is that it does not need or want a Hall sensor. Am I wrong?

In a way you are spot on it is a 'school girl circuit' a bit sexist i suppose! however i think the idea was to create the "effect" as simply as possible, anyone can create the SG circuit without any electronics knowledge at all, making a good setup with a hall or optical really needs a scope and some basic electronics knowledge.
the amount of inductive kickback with this circuit is higher than i have seen with any inductively triggered circuit (on the same spool).
JB says that you have to build at a higher level if you want to go further, the sg is just a simple introduction to the idea.
I will post my final simple schematic so everyone can have a go, my first one was incomplete so dont bother with it.