Open Collector?

[Kari Laine]

Hi,

I just built Velleman 8061 and got it eventually working - I think?

But I have a question.

Shouldn't I be able to see whether line is active by resistance meter
over the transistor?

If I have understood right the resistance over the transistor should
change when line is on or off?

Now the resistance meter shows only infinity whether the line is 0 or 1.

I can't understand ...

Best Regards
Kari

--
PIC - ARM - DISPLAYS - RELAYS - MODULES - CONVERTERS - I2C - SPI -
KEYPADS - ACCESSORIES
http://www.byvac.com (I am just a satisfied customer)

 

[Peter Bennett]

On Tue, 27 Apr 2010 17:50:39 +0300, Kari Laine <klaine8@gmail.com>
wrote:

Hi,

I just built Velleman 8061 and got it eventually working - I think?

But I have a question.

Shouldn't I be able to see whether line is active by resistance meter
over the transistor?

If I have understood right the resistance over the transistor should
change when line is on or off?

Now the resistance meter shows only infinity whether the line is 0 or 1.

I can't understand ...

Best Regards
Kari

Connect a resistor from a digital output to the positive supply, then
measure the voltage between the digital output and ground.


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

[John Fields]

On Tue, 27 Apr 2010 17:50:39 +0300, Kari Laine <klaine8@gmail.com>
wrote:

Hi,

I just built Velleman 8061 and got it eventually working - I think?

But I have a question.

Shouldn't I be able to see whether line is active by resistance meter
over the transistor?

If I have understood right the resistance over the transistor should
change when line is on or off?

Now the resistance meter shows only infinity whether the line is 0 or 1.

I can't understand ...

---
Try this: (View in Courier)


C-------+
VIN>---[R]----B NPN |+
E [OHMMETER]
| |-
GND>------------+-------+

or this:

C-------+
VIN>---[R]----B PNP |-
E [OHMMETER]
| |+
VCC>------------+-------+

JF

 

[Kari Laine]

Peter Bennett wrote:

On Tue, 27 Apr 2010 17:50:39 +0300, Kari Laine <klaine8@gmail.com
wrote:

Hi,

I just built Velleman 8061 and got it eventually working - I think?

But I have a question.

Shouldn't I be able to see whether line is active by resistance meter
over the transistor?

If I have understood right the resistance over the transistor should
change when line is on or off?

Now the resistance meter shows only infinity whether the line is 0 or 1.

I can't understand ...

Best Regards
Kari

Connect a resistor from a digital output to the positive supply, then
measure the voltage between the digital output and ground.

THANKS !



--
PIC - ARM - DISPLAYS - RELAYS - MODULES - CONVERTERS - I2C - SPI -
KEYPADS - ACCESSORIES
http://www.byvac.com (I am just a satisfied customer)