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  1. dorke

    ZIF-sockets from eBay etc -quality OK?

    TTL, Most probably fakes. The question is how many times you intend to "insert and remove" parts from the sockets?and for how many years? The problems are corrosion with time and grip quality with number of insertions. You want get far with Chinese parts they are mostly bottom reliability ...
  2. dorke

    60 Hz line frequecy divided to 1 pps

    If your goal is to make an "accurate clock" ,you are on the wrong path. Use a crystal oscillator, not the line frequency. Commercial clocks use the 32.768KHz crystal which is very common and dirt cheap, add an osc. and divider IC like the 4060 or 4521 etc. Note that there are Single IC clock...
  3. dorke

    120VAC --> 12V LED chip

    Safety first, If you don't understand how it works, it is most probably unsafe for you to build it!!! It is simple, but it is the wrong way to drive an LED. LEDs are "current driven creatures", this circuit does a poor job of driving the correct controlled current value through the LEDs. The...
  4. dorke

    Multimeter Spec

    Let me add , If you want to make a meaningful accuracy comparison you should have a device that is at least 10 times more accurate than the one you are testing. Regarding accuracy , the ExTech EX505 isn't better than the Hyelec MS89 ! In fact, the MS89 is the more accurate one. In DCV the...
  5. dorke

    DT 9205A digital multimeter

    Actually you can simply try and discover the correct position to match the writing on the case. The switch is a 360 degrees rotatory one,turn it and try to find the diode/continuity position. Do this: Insert test leads and short them permanently together. Rotate the switch till you hear the...
  6. dorke

    Before powering a circuit.

    Yes, it depends heavily on the circuit. Is it a newly developed one? Is it a kit? etc. I would suggest this: 1. Check ohmic values of power lines to ground and other power lines , same for inputs and outputs, to be the expected values. 2. Use current limited power supplys with current...
  7. dorke

    What is this component? Repairing a circuit

    Most probably, Electrolytic, polarized, should be around 100uF and up, voltage 400-500Volts. They can deliver a nasty shock, there are bleeders connected, but still) don't touch . Need more photos of the caps (more writing on them), the PCB etc.
  8. dorke

    Volkswagen VDO analog clock repair

    One small note: The crystal frequency is 4.194812 MHz =4194,812 Khz.
  9. dorke

    Audio desk

    Like my fellows said, slim chance to use this board. If you care to re-use the audio desk, you can try and fit this cheap Bluetooth board (or alike). Maybe add a more powerful audio amp. as well.
  10. dorke

    Faulty 9VDC Power Supplies

    I meant the current of the 9V and the current of the 24V. If you know the currents you now the wattage W=v*I .
  11. dorke

    Faulty 9VDC Power Supplies

    You can try and fix the broken coil with glue and solder the broken leg. It should work fine if the coil isn't burned. What is the current of the 9V and the 24v? It is the wattage that meters in regard to the coil and it's configuration. Can you ohm test the coils?
  12. dorke

    Faulty 9VDC Power Supplies

    This "coil" is an EMI (Electro Magnetic Interference) line input filter. It is used to filter out(with the surrounding caps) the noise created by the SMPS(Switch Mode Power Supply) from reaching the line. The "coils" have different configurations and specific values,you need to know the...
  13. dorke

    Faulty 9VDC Power Supplies

    You don't need to replace the cap if it isn't bad. But you can while you are already "at it". The higher voltage isn't a problem,the new cap should be"low ESR" type" . If the coil is broken replace it as well.
  14. dorke

    Faulty 9VDC Power Supplies

    BTW, That Chinese CapXon brand is very well known for making crappy failing power supply caps. I have replaced quit a few of them myself.
  15. dorke

    Digi pot for pwm board

    The PWM duty cycle POT. works as a voltage ratio divider to set the duty cycle. So it can be 100K instead of 10k (there is no limit for it ,only regarding leakage currents) , it will work fine,no need to change anything simply replace it from 10k to 100k. Yes, the Schmidt and stuff has to do...
  16. dorke

    laser ttl module

    Unless you want to blow-up all the TTL ICs (smoke isn't guaranteed but they will blow and crack). Anything above 7V would do a good destruction work.;)
  17. dorke

    Digi pot for pwm board

    Here is a simple circuit that may work for manual switch operation. First you select the pot you want to operate and the direction, then you push the INC switch for a "single step".
  18. dorke

    Digi pot for pwm board

    You can operate the 100k/256 steps MAX5454EUB device with switches(and some simple logic). It is a dual device which can cover the 2 pots you replace in a single IC.
  19. dorke

    For Sale: Chips and resistors

    The list is of the Mid 80's parts,mostly not used anymore. I suggest you put them for sale on Ebay as "old stock" with per piece price. Even so,they would be very hard to sell.
  20. dorke

    What is this contactor? Where to get it?

    Do you have the part number and make of your original contractor?
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