Hello everybody,
my question concerns the K8055N PWM-Signal. I’ve connected a 12V AC source with a 1K resistor like explained in the manual to get the pwm-signal. When I watch it at an oscilloscope the low level isn’t at 0V, but about 5V.
Using the same installation at an K8055 ( without N ) the result looks as I need it.
Are there some Ideas why this happens?
Thank you a lot for every comment.
Greetings
Johnny
The PWM output should be able to pull down 100mA.
The 1k at 12V should not be a problem.
Please check the transistors T1 and T2 (BC337) are properly installed.
[quote=“johnny”]Hello everybody,
my question concerns the K8055N PWM-Signal. [color=#4000FF]I’ve connected a 12V AC source[/color] with a 1K resistor like explained in the manual to get the pwm-signal. When I watch it at an oscilloscope the low level isn’t at 0V, but about 5V.
Using the same installation at an K8055 ( without N ) the result looks as I need it.
Are there some Ideas why this happens?
Thank you a lot for every comment.
Greetings
Johnny[/quote]
Are you actually using a 12 VAC source, or an AC powered supply that provides 12 VDC?
Hi,
I’m sorry. This was a typo. I’m using a power Supply with 12V DC.
I’m also actually using the pre assembled VM110N Board and the behaviour appears on both pmw-outputs, so I don’t think it is a Problem with the transistors. The signal does also have the right rectangular shape with the correct duty ratio. Just the off voltage is not correct.
[quote=“johnny”]Hi,
I’m sorry. This was a typo. I’m using a power Supply with 12V DC.
I’m also actually using the pre assembled VM110N Board and the behaviour appears on both pmw-outputs, so I don’t think it is a Problem with the transistors. The signal does also have the right rectangular shape with the correct duty ratio. Just the off voltage is not correct.[/quote]
It should be working, with the low PWM output being around 100 mV. Have you checked the DC supply output for any anomalies?
You could also probe the VM110N, check the base-emitter signal on T1 or T2 (ground probe to the emitter) and make sure it is behaving as it should.
Here are scope traces of the T1 VBE and PWM1 output of my K8055, using the same setup (+12V and a 1kΩ resistor):
You should see similar results with the VM110N board.
To our valued customers:
It has been brought to our attention that the 2N2222 in TO92 can have two different pin-outs.
Most likely, if you swap the outer pins of T1 and T2, it will work correctly.
Should you wish to receive two spare transistors, please let us know your address.
Precautions have been taken so that future batches will not be affected by this problem.
Sorry for the inconvenience.
Thanks for the answers.
Did I understand it right, that swapping the pin out of the transistors will solve the problem? That would be a very good news.
How can I contact you to send me two spare transistors, as I don’t think the pins are long enough to swap em easily.
greetings Johnny
Yes, please try to swap the outer pins.
(You have received an email)