Will this circuit work, and how much power will I need?

Discussion in 'Electronic Basics' started by smpaladin, Oct 18, 2004.

This is a depiction of a circuit that I am planning to make.

It is a linear motor; Whenever a magnet is passed over the hall
sensor, it turns on the Power transistor, and therefore turns on the
Electromagnet coil. In the picture, there are only four sets of the
hall sensor/transistor/coil. In the real circuit, I am planning on
having 12 sets of them.

So will this circuit work properly? And how much power will I need?
You would think that the circuit would need a lot of power, but then
you realize that only one set of the hallsensor/transistor/coil will
be turned on at any one time.

2. Rheilly PhoullGuest

OK, so all you really want to know is the current for one section. No one
can tell you unless the details of the coil and battery are shown. I.e
battery voltage and details of the coil. Always include that sort of info
when asking this type of question. Also what the device is required to do

Each coil consists of 15 ft of magnet wire (i'm not sure what type of
magnet wire, but its slightly thicker than thread) wrapped around a
1/4 inch thick screw. The coil should be strong enough to attract and
get a hold onto a similar sized screw from about 1/4 inch away (That
works with one set of hallsensor/transistor/coil, but the question is
will it work with 10 sets connected to eachother).

The transistors are PNP TIP106, and the hall sensors are PNP 21E.

4. rayjkingGuest

You also need to add a resistor in series with the transistor base to
protect the halls and connect a clamp circuit across the motor coils to keep
the transistors from failing.
The motor rpm is limited by the rate of current build up and should have the
same rate of current decay or faster. What ever the battery voltage is the
clamp should be higher. one way is to add a clamp diode across each motor
coil with a zener diode in series with the clamp diode that is at least 30%
higher than the battery voltage. The transistor voltage will see the battery
voltage + 30% + the battery voltage.

Fets are best.

Ray