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cimo

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Posts posted by cimo

  3. Another crazy DMX project

    in Design Concepts

    Posted

    So far: with up to 35W lamp per channel it works as a charm with the latest schematic, just a single bc547 and a couple of resistors. Problems come with a 50W lamp and up, it can tswitch it on completely or turn it off completely depending on the resistors value i use.

    From what i ve learned these days, i am not supplying enough current to the 2n3055 be junction so the transistor can handle all the current required by the 50W lamp, over 4A.

    My plan was to go all the way up to 70W per channel.

    Would that be a good idea to use another transistor instead of the bc547? maybe something that can handle more current? Or is it just a matter of using the proper resistor value?

    Thanks

  5. Another crazy DMX project

    in Design Concepts

    Posted

    Just looking at your circuit, is there any reason why the load is wired between the emitter and ground?

    Usually you would place the load between collector and ground (with the emitter directly grounded).

    i ve changed it and it seems to be more responsive this way

    See the attached shematics, i understand why it s inverted but i don t understand why if i reply the same circuit and add in serie as i had it before it is still inverted, am i missing something?

    thanks

    screenshotpy8.png

  6. Another crazy DMX project

    in Design Concepts

    Posted

    Well it is working but:

    1- it s inverted, when the dout is on the light goes off

    2-it s slow to power on and off (???)

    3-i can t really reach a perfect no-light and full brightness

    The change have been reducing all values of the resistors as suggested by Philtaylor

    I d really appreciate any kind of help.

    Thanks

  8. Another crazy DMX project

    in Design Concepts

    Posted

    hheeelllllpppp

    The first stage works, i get 12 volts at every pulse from a dout but somehow the power stage does t get activated an di think that maybe the first stage can t supply enough current to trigger the power transistor. I measured just 1mA between the 2 stages that is between R3 and Q3 base.

    Which resistors should i change to increase the current available at the output of the fisrt stage?

    thanks

  10. all led lights and mios don't load

    in Testing/Troubleshooting

    Posted

    Tilted 1 -- Cimo = 0  >:(

    dout with two interrupts

    din with 64 leds

    this is incorrect, just a typo?

    I must to say i have wired badly the dout the first time and i wondered if i had not burn the shifts registers ( especially sclk and rclk because they "taked 5V on the teeth" the first time  Embarrassed).

    that should n t be  a problem, but i ve destroyed some 74165s just with static

    I tried dout_button test and , when i start midibox, mios don't load and all leds are lights.

    When i try the same with only one dout x4 and the first shift register on it, the test works fine ( one led lights sequentially with one interrupt).

    Can you try to swapt the 2 SRs on both the placements? In this way you can bu sure if they are ok or not

    Simone

  17. Another crazy DMX project

    in Design Concepts

    Posted

    Just an uptodate for you to follow up:

    Thanks to Reichelt s cheap prices and Lucem advice i came up with the following:

    -Each group of light will carry 3x 50W (12v) halogen lights.

    -Each group will be connected to a DOUT with 2 bc547 and a final power stage with a 2N 3055, the power transistor will be mounted on a large heatsink and i ll use 2mm² copper wire to connect the transistor to the pcb and to the battery

    -I ll solder close to each transistor 3x 4700 uF capacitors

    -All cables from the transitors going to the battery will be tied together directly on the battery, avoiding having a single cable to carry the whole current.

    ... more ideas ?

  18. Another crazy DMX project

    in Design Concepts

    Posted

    mmm

    let s go back to the 12 volts idea.

    I ll have, let  say, 16 outputs with 2x 40W/12v (6.7A)

    That makes for 108A, that would be for maximum load.

    battery<-->108A<-->distribuition box<-->6.7A<-->"light block"

    My only worries are about the PCB that will carry the transistors, since there would be a considerably load of current on the copper layer.

    MRE: i was not planning to use step down transformer with the 220v setup, and i don t understand: a 12 volts 50W light requires a thicker cable than a 220 volts 50W one, doesn t it?

    Simone

  23. What's the trick with installing the trimpots in the SmashTV CORE?

    in Parts Questions

    Posted

    http://en.wikipedia.org/wiki/Potentiometer

    http://en.wikipedia.org/wiki/Cable

    http://en.wikipedia.org/wiki/Control_knob

    http://en.wikipedia.org/wiki/Control_panel_(engineering)

    sorry just a bit in a hurry, hope that helps

    You could actually dim the brightness and therefore select contrast rate using a pwm on some free pic s pins but that has never been done before as far as i can remember.http://en.wikipedia.org/wiki/Control_panel_(engineering)

  24. Another crazy DMX project

    in Design Concepts

    Posted

    re: thick cables, it seems you'll want those for 220v anyways...

    but that would be just for the 12 volts path then i could use 1mm cable formt he inverter to the ditribuitor and then just 0.75mm.

    i have an led flashlight that throws a beam several blocks, brighter than any of my regular ones...

    maybe consider getting some of those in bulk and replace the switches with relays or likesuchas...

    ok, more details: we are desperately short on money, and time for that it matters.I am going to use those Triacs with, in case, some optoisolators, btw any advice for optoisolators that can be found at Reichelt or RS Components?

  25. Another crazy DMX project

    in Design Concepts

    Posted

    good points but i forgot to mention some details:

    reconsider strapping a homebrew 220v system on a person, unless you want them to fry.  even if you get lucky there, the heat may kill...

    why not leds?

    -I am not going to strap stuff on her body, she s going to carry a 200-300 kilos wheeled "stuff" and the system is going to be inbuit there, and i can also isolate the parts that she is touching form the rest of the frame

    the battery will need to supply the necessary power regardless of final voltage, so your current out of the battery will be high anywayz.  unless you are driving very long lines, the transformer efficiency will actually increase your power requirements.

    -The idea is to use a step up transformer so the only "thick cabled" connection would be 20-30 cms

    car batteries are not designed to handle repeated charge/discharge cycles.  you'll want a marine battery instead. 

    -The whole thing will last only 210 seconds and only once

    lead acid batteries give off hydrogen when they charge, and can explode if an internal short happens.  this is especially nasty because of the sulfuric acid.

    -Would a sealed plastic box be of any help?

    dc thru a transformer will not work, you need an ac inverter or likesuchas for that.

    -Yep, that s what i meant, i just used the wrong word

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