hi all.
I've been developing a very specific random light controller using a picaxe 40X1 and i'm at the stage now where the programming part is almost done and i need to drive the intended lights from the picaxe..
I'm not an analogue electronics expert, I troubleshoot microprocessor based digital microelectronics in my usual job, so i'm a bit vague on analogue stuff and wondered if someone could comment on my selected circuit...
I am driving a number of miniature 11w fluorescent tubes, these use OSRAM electronic ballasts (QTFM 1x11's).
Shamelessly found on the internet, i modified the opto-driven TRIAC circuit found here :
http://www.mitedu.freeserve.co.uk/Circuits/Switching/triacctl.htm
I just removed the 470R and LED and substituted the 3040 with a Motorola MOC3020 (more plentiful). I'm Also using a BTA10 TRIAC, because i have a drawer full more than any other reason I'm also using 20mm fuseholders/fuses to aid in servicability. The fuse selection i was unsure of, but i figured to try as low as possible, my rudimentary calculations say 0.04 amps at 240v is required for the 11watt tube and electronic ballast, but i thought i'd scale up slightly, i have 100ma and 500ma fuses in stock, but currently i have only run the test circuit with a 1amp@240v fuse.
I built one example circuit on a stripboard and left it running the lamp with one of the 14 outputs i'm using on the 40X1.. for a few hours... The PICAXE turns the light on and off randomly, on and off times range from 2 seconds to 3 minutes. The triac didn't even get hot, nor did the opto driver, so i'm taking that as a good sign, the cooler this runs, the better as it will be enclosed with 13 other identical circuits..
my main questions for you all is:
- What rating of fuse should i go with? 100ma, 500ma ? or am i off?
- Do you think the circuit is suitable, could it be improved? have i made any dangerous assumptions?
- The BTA10 (400B) triacs are isolated tab, i was thinking of bolting these to an aluminium bar heatsink to share the heat dissipation (if any). Is this reccomended?
I thankyou in advance for your input, i love the forums here, and i love the picaxe, i have so many projects in my head it will take me a while to bring them all to fruition... Like i say, my background is much larger CPU based systems troubleshooting, small microcontrollers have always grabbed my attention, but i just havn't had the time until recently to get stuck in, and i don't come across them often (i work on stuff from 1971 to 1984 mainly)..
I've been developing a very specific random light controller using a picaxe 40X1 and i'm at the stage now where the programming part is almost done and i need to drive the intended lights from the picaxe..
I'm not an analogue electronics expert, I troubleshoot microprocessor based digital microelectronics in my usual job, so i'm a bit vague on analogue stuff and wondered if someone could comment on my selected circuit...
I am driving a number of miniature 11w fluorescent tubes, these use OSRAM electronic ballasts (QTFM 1x11's).
Shamelessly found on the internet, i modified the opto-driven TRIAC circuit found here :
http://www.mitedu.freeserve.co.uk/Circuits/Switching/triacctl.htm
I just removed the 470R and LED and substituted the 3040 with a Motorola MOC3020 (more plentiful). I'm Also using a BTA10 TRIAC, because i have a drawer full more than any other reason I'm also using 20mm fuseholders/fuses to aid in servicability. The fuse selection i was unsure of, but i figured to try as low as possible, my rudimentary calculations say 0.04 amps at 240v is required for the 11watt tube and electronic ballast, but i thought i'd scale up slightly, i have 100ma and 500ma fuses in stock, but currently i have only run the test circuit with a 1amp@240v fuse.
I built one example circuit on a stripboard and left it running the lamp with one of the 14 outputs i'm using on the 40X1.. for a few hours... The PICAXE turns the light on and off randomly, on and off times range from 2 seconds to 3 minutes. The triac didn't even get hot, nor did the opto driver, so i'm taking that as a good sign, the cooler this runs, the better as it will be enclosed with 13 other identical circuits..
my main questions for you all is:
- What rating of fuse should i go with? 100ma, 500ma ? or am i off?
- Do you think the circuit is suitable, could it be improved? have i made any dangerous assumptions?
- The BTA10 (400B) triacs are isolated tab, i was thinking of bolting these to an aluminium bar heatsink to share the heat dissipation (if any). Is this reccomended?
I thankyou in advance for your input, i love the forums here, and i love the picaxe, i have so many projects in my head it will take me a while to bring them all to fruition... Like i say, my background is much larger CPU based systems troubleshooting, small microcontrollers have always grabbed my attention, but i just havn't had the time until recently to get stuck in, and i don't come across them often (i work on stuff from 1971 to 1984 mainly)..