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  1. Minder

    Make electronics : experiment 8 problem

    You need to identify the actual relay used, some also have the common for the contacts in different positions. M.
  2. Minder

    Make electronics : experiment 8 problem

    Usually the bottom two of the relay is the coil, you appear to have the connections mixed up? M.
  3. Minder

    I2C (Inter Integrated Circuit)protocol

    I2c was originally developed for attaching lower-speed local peripheral IC's to processors and micro controllers and has the advantage of multi drop slaves from one master, similar to the longer capable distance Modbus e.g.. UART (RS232) also has longer distance capability and transmission can...
  4. Minder

    why we use ports ?

    In computers there are also physical connection ports to the outside world COM port,Parallel Port, USB port etc. These are not to be confused with the ones already stated, physical pins on the processor. M.
  5. Minder

    DC motors and speed control

    I looked up the standard MC-60 and it uses D4020L & S4020L which are 20 amp devices, so if you have it fused for 15amp, which is the rating for your 120vac outlet, you should be OK, in any case the parts are easily avail form Digikey and you could up the current rating if ever replacing. M.
  6. Minder

    DC motors and speed control

    You could also check the part # of the switching devices, if SCR bridge, the diodes and SCR's are usually Teccor (now Littlefuse) or close equivalent. Check the current rating. M.
  7. Minder

    Watchdog Timers

    To me a hardware WD or charge pump is a circuit external to the main controller and can involve hardware in the form of relay etc used to control external devices, this monitors the state of the main control where a pulse or signal is sent to the external HW WD. The S/W WD is one that is used...
  8. Minder

    DC motors and speed control

    Your loading of the motor is the deciding factor as to wattage, also the rate of acceleration, the application you may be using the motor in is most likely very different from the TM, where the motor was fitted with a Heavy flywheel and was accelerated/decelerated very slowly. With controllers...
  9. Minder

    Is this circuit compatible for charging my gel cell?

    See this link based on MAX712. http://www.rason.org/Projects/gelcell/gelcell.htm M.
  10. Minder

    DC motors and speed control

    Should be OK, as long as you switch with low/no current, i.e. motor stopped. M.
  11. Minder

    DC motors and speed control

    The reversal has to be done on the motor leads, on the switch you show, the motor DC feed would go to the centre pair, the motor would go to an outer pair, then take a wire from one outer to the opposite outer terminal for each. (Criss-cross). Remember to take the speed pot to zero RPM before...
  12. Minder

    What basic transistor I can use for simple PWM

    PWM control especially motors is done now commonly controlled with Mosfets, these have the advantage of very low on resistance and also have the option of TTL Logic level gate compatibility. You can get some that have the current sense built in for external monitoring, alternatively a very low...
  13. Minder

    What Potentiometer should I get to control the speed of a computer fan?

    You mean apart from post #5? M.
  14. Minder

    What Potentiometer should I get to control the speed of a computer fan?

    A potentiometer is not a really recommended way to control a motor directly, it is very wastefull in power also. M.
  15. Minder

    What Potentiometer should I get to control the speed of a computer fan?

    If you want to guarantee a simple form of control, then DC brushed are generally the simplest, the older PC fans were practically all this type. M.
  16. Minder

    What Potentiometer should I get to control the speed of a computer fan?

    A BLDC motor operates from a DC supply but requires commutation to the 3 stator winding, so There has to be embedded electronics of some kind. Picmicro TC653 etc M.
  17. Minder

    switching device

    I believe I have seen a commercial one, there are data switchers that could be easily put together, http://datasheets.maximintegrated.com/en/ds/MAX4947-MAX4948.pdf You can get higher voltage and smaller package types also. M.
  18. Minder

    Help on how to test this device

    That just appears to be a outer cover strip, the lamination's look intact to me. M.
  19. Minder

    What Potentiometer should I get to control the speed of a computer fan?

    There are many PWM on ebay for $5.00 pp 291341338166 Circuit here http://www.discovercircuits.com/DJ-Circuits/simplepwm2.htm You might have a problem with current fans as although they are DC fed, they have an internal PWM controller IC. M.
  20. Minder

    Ratings for AC vs DC devices

    The DC rating does not equal the AC rating in switching or disconnection device especially when inductive devices are used. M.
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