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Posts posted by electrodoc

  1. Had a bit of spare time so i did a sketch of a simple interface for the printer port.

    This was an original concept by myself to intergrate both my courses at college (electronics and I.T.) to control stepper motors in the cruedest of ways.

    It did work though and all the other guys where around my P.C. for .. ohhhh at least five minutes as i'd ask them where they wanted a pencil blue tacked to the top of the motor to point when it came to rest.

    With gearing however it would be very precise, speed was limited due to relay latency. speeds of appx 3 revs a second where attainable though. and it was only a pencil pointer after all.

    Ohh BTW this was some time ago and I have a nagging feeling that output 1 maybe the second hole in from the left on the top row. (someone shed light please). haven't time to look got to buy a setee (couch)..

    Bye Rich.

    P.S. still needing an exe file for my bingo program in last post ;D


  2. i had the vision of building one of these babys before and it's been re kindled after watching the 2nd series of pheonix nights.. lol

    Both using a tape and using a digital voice recorder are viable but as the tape decks are easy to come by and have a solenoid, magnetic reed switch, heads and the motor, it would be much more enjoyable to watch it work and it will bring you closer to understanding the fundementals of step by step electronic sequences

    Using a 4017 cmos decade counter or two with this kind of project, will keep it simple and YOU will know every piece of logic going through your project.

    Firstly think of what your project needs to do, in steps..

    1>__"armed" use output '0' to hold the clock enable pin on the 4017 to ground this logic state could also supply power to your intruder sensor, if required.

    2>__"Trigger".. Hold the clock enable pin to + momenteraly and the count begins on the next clock pulse.

    3>__"cassette rewound"?. output '1' goes high, throw the motor into reverse for a few seconds or until no more pulses are recieved from the reed switch (this can be achieved using "initiation by supply" configaration of a 555 timer). this will tell your clock to start counting again or lift the clock enable pin high again.

    4>__"Amplifier on" output 2 switches a relay that applies power to the amplifier.

    5>__"Wait for reset" output 3 is connect via a 4148 diode to output 2 in such a way that output 2 still applies power to the amplifier

    6>__"play message" output 3 also inhibits the clock of its own chip but allows the 2nd 4017's clock to enable. a 2 input and gate with the clock pulse on 1 of the inputs and the output from 3 on the other input would do the job of supplying a clock pulse to the 2nd 4017.

    7>__"playing loop" the second 4017's output "0" is high on the next clock pulse output "1" is high this pin applies power to the solenoid and the motor (forward running)

    8>__ on the next clock pulse output "2" goes high, this can be used to break current to the solenoid but keep the motor running.

    9>__ the next bit depends on your clock frequency.. if your running at 1hz then each output of the 4017 will be high for 1 second therefore you can use upto 8 seconds by having all the other outputs holding the motor on (plenty of recording time to say "GET BACK YA BAS**RD, I'LL BRECK YA LEGS!!. However, the last output "9" needs to rewind the tape using the description in para 3.

    there maybe problems over looked as this is the first time i've explained it so indepth, there are obviously shortcuts or design enhancements that can be made but these would be on the breadboard stage.

    I also think your tutor maybe more impressed with the whole programming to wiring of this project. if LED's where added and labeled for each of the different inputs, outputs and inhibits of the components it would be a great training tool. Any probs then i'd be glad to assist.


  3. the tda2506 seems to be a secam decoder tried to search but found that but nothing on my s/engines for that number.. tried a few though.

    is it a car stereo? if so put a couple of phono leads through the back and feed them to a seperate car amp.

    try the links yourself if you want


  4. it certainly does look like a jungle chip.. here you go.. wow that took some finding!!

    it seems to be a replacement for the 8680 despite having a completely different number. 1 of the links is for the data sheet the other is a link from a link that was linked in a link from a search submitted to google and its where i found the datasheet.

    this searchengine seems good as you can do a search on the TA prefix to find the manufacturer, which was philips or toshiba (searching both these sights returned no results btw).


  5. I don't know your skill level so i'll explain it basically.

    The most common cause is the line output transistor, take it out and check it with the legs pointing towards you and the writing facing upwards, set your avo on diode check (if its digital meter) or the lowest setting you have for ohms on a moving coil meter, put one probe on the far left leg (base) and the other probe on the centre leg (collector), then reverse the probes. one way around you should get about 400 to 800 ohm reading and the other way around you will get no reading. if this isnt the case then the trany is shot but usually for a reason. check the joints around the eht transformer for bad connections and the scan coils on the back of the tube may have a plug going to it, if so then check the connections on this plug AND the connector to the main board from the coils. if any of the connections look cracked then resolder them.

    see how you go with that for now and let me know..

    Bye. Rich..

  6. If someone can make this an exe file that would be great!

    please mail it back to me as the stand alone file..

    you will need Qbasic to run this program and thats available in the win98\tools\oldmsdos directory on 98 cdrom.

    Qbasic works fine on 98 and all predisesors but i'm not sure about XP or Xtra Problems as i like to call it.

    There are no printer port commands in this program so no need to disconect your printer etc.

    p.s. when using the program make sure CAPS lock is on. and don't go selling it to a pub/club ok. 8)


  7. thanx again Mike. i got QB4.5 but when i try to run my program i'm getting a "String Space Corrupt". it's a shame because i've wanted my bingo program to run as stand alone, I may even make a 8X16 light box to display the numbers from the program to the people who are playing.

    i wrote this for the spectrum at first in exactly the same way as i have for the p.c. with the two arrays, as you can imagine when the specy got up to the 70th number or so it REALLY slowed down. so i got it to randomize 86 numbers of the full 90 then it only took 5 minutes or so LOL. (just enough time to sell the tickets and work out the winnings) at grandma's boxing day parties. however i was astounded at the low spec p.c. i rewrote it for. You don't even see the "Now randomizing ball number" screen come on! and thats randomizing all 90 numbers!

    If people out there can see the scope of what interfacing a p.c. and your projects can do, then go out and buy a little 386 or better still get one given you! or a 486 anything that will stand alone and run qbasic.

    Cheers Rich.

  8. I didn't have to fool the port into thinking anything was connected to it i used a 386 DX 40, a 20 mb hdd with dos on it typed in Qbasic:-
    10 x = 1
    20 Out 888,x
    30 pause .5
    40 x = x+x
    50 if x => 16 then x=1 else goto 20

    this would revolve the stepper motor until you ended the program. the use doesn't end at stepper driving you could have pin 1 as a clock pulse and pin 2 as a data line.

    I think qbasic is perfect for this application as it is very much like spectrum/commodor/bbc 1980's programming languages and the help files are really handy with there copy and paste features which help when you're of the self teaching techy + the added advantage of only needing an operating system and the qbasic program itself.
    you could switch on the whole house from a floppy.

    I am open to other suggestions as regards a programming language but this was one i stumbled across whilst writing a bingo program and i was led to the "out" function whilst using the afore mentioned help files whilst writing it.

    Before trying this, disconect your printer it may damage it!!!!

    You can use your printer port as a controller for electronic projects. get QBASIC either from a dos disk or windows95/98 cd rom and run it then if you type in "out 888,1". This will send pin 2 of your printer port to +5 volts, to reset it back to 0 volts type in "out 888,0", The port has 8 binary outputs this is controlled by the "out" command. 888 is the number of the port you are addresing (printer port) and the second number corresponds to which of the 8 outputs you want going to +5 volts.

    to set all of the 8 outputs to + 5 volts type "out 888,255". this is a very handy tip because when i was trying to control a stepper motor from my P.C. i couldn't find anything simple in which to do it but there you go enjoy.

    also remember that this thing can switch states incredibly fast! and what ever you wish to interface can be done easily with a little basic knowledge of computer programing.

    There is also the "IN" command which will read the state of the printer ports particular bit so you can have full interaction with your P.C. and your projects, I've never used the "IN" command on a project but i've browsed notes in magazines etc so i know it's possible.

    Bye.. Rich... ;D

  10. Hi,
    Long time hobbiest first time op amp user!

    PLEASE would someone help as i cant get to grips with the formula for bandpass filters/gain or anything regarding electronic filters.!

    All I want is a phisicaly small high gain low frequency filter circuit which will use a xtal/moving coil mic to make a bulb flash to the bass beat of music (appx 40hz - 100hz) the voltage would be 3-9 volts and i'd like to use a dual opamp with a single supply line. unless theres a transistorised version anyone can think of.

    Thanx in advance.. Rich

  11. Hi Si.. you need to have the tilt switch normally open when the bike is on one side, then have the tilt switch put a + supply onto the trigger (pin 2) of the 555. the output will then go high for the duration of your CR network after the bike is left alone. I'd also put a high value 4k7 resistor from pin 2 to ground to prevent mistriggering. to prevent any damage due to voltage spikes I'd use a diode or a bridge rectifier and a smoothing capacitor before the supply gets to the circuit. A good book on this subject is Bernard Bapanni 555 timer projects

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