Re: magnetic sensor to PC interface

On Mar 7, 9:07 am, pete_tom...@xxxxxxxxxxx wrote:
Hi All - I found this newsgroup and was wondering if anyone could help
me.
I'd like to connect a magnetic sensor (bicycle computer) directly to
my computer through one of the ports without a power supply.

Are you mounting a computer on your bike?


Basically the reed switch will have a current induced in it so I'm
thinking I'd ideally like the circuit to be passive with minimal
external circuitry.

It will not have enough power to run a micro.
The best way is to get power from USB,
whether you interface to it or not.


I have a pic of a basic circuit I found but don't know how it works
and I don't know how to post it. Basically it has a connection to pin
4 through a 4.7kohm resistor a direct connection to pin 6 and a ground
through pin 20.

You need to amp the signal.
4.7K to VCC and 100s ohms between op amp ouput and port.

If you tell me how to post a pic I can show the diagram.

Can anyone make suggestions about circuit design - can I feed the
wires directly into my parallel/serial port?

Probably not.


I'm also trying to write a program in VB6 to read the input, but not
having much luck.

Depends on the OS as well.


I'd really appreciate any help anyone could give me.
Thanks
Pete


.

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