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Need help with driving 2N2222 transistor with EM1000
I am trying to drive a 2N2222 using an io line from the EM1000 in order to open/close a 5V relay. The 2N2222's base is connected to the io line via a 1K resistor.
The problem I have is that when I try to change the state of the io line to LOW it just stays at HIGH. I can't get it to go LOW. When I disconnect the 2N2222 from the io line and try again it finally reports the state as LOW. The weird thing is that there is always at least 1.5 V on the pin, whether it is HIGH or LOW.
What is going on here? And why won't it go LOW when the 2N2222 is connected?
The problem I have is that when I try to change the state of the io line to LOW it just stays at HIGH. I can't get it to go LOW. When I disconnect the 2N2222 from the io line and try again it finally reports the state as LOW. The weird thing is that there is always at least 1.5 V on the pin, whether it is HIGH or LOW.
What is going on here? And why won't it go LOW when the 2N2222 is connected?
I’m confused
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Inappropriate?Thanks for the reply Mauro! Yes, I did set the pin as output.
I cleaned the stripboard I am using and that solved the problem for me. Must have been some current leak from an adjacent strip...
Thanks again for the reply!!
I’m amused
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Inappropriate?Maybe some varnish was conducting a small current.
For your info we have written a RS232 Device Server for EM1000 suporting wireless.
It is available in source for a small fee. If required we can develop a 4 ports similar solution.
If I can what is the final target for you project? 2n2222 is my favourite transistor since i was a boy. I put it everywhere.
Regards
Mauro
I’m happy
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Inappropriate?It could definitely have been the varnish.
I am building a relay controller for activating water pumps for irrigation. The pumps can be manually started and stopped via the web interface or the process could be automated to start the pumps based on certain events.
I am finding these Tibbo devices very cool so far! Thanks Tibbo!
I’m excited
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Inappropriate?Use an optoinsulator(LED+transistor) to activate it: you won't regret! I have projects running since 1980 in such a fashion. You can keep driving current separated from EM1000 Vdc. No more spikes(from relay coil).
Yes I agree TIBBO mades it very easy!
Happy Celebrations!
Mauro
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Inappropriate?Thank you Mauro
I am interested in this optoinsulator you are talking about. I am currently using a flyback diode for protection against spikes from the relay coil. Are you putting an LED in series between the relay coil and the 2n2222's collector?
Happy Christmas to you too!! -
Inappropriate?http://www1.jaycar.com.au/images_uplo...
there is a very nice schematic of a optocoupler use to drive a TRIAC. You can use it exactly as a transistor. Reduce the current on CPU I/O and forget spikes. My favourite device is 4N25, cheap and capable. It can drive a relay directly or a transistor's base, depending on current.
You can change it in seconds if it burns.
Look at this too:
http://www.geocities.com/dsaproject/e...
ciao
Mauro
