Search results

Search Forums New Posts
  1. duke37

    24vAC to 9vDC: half wave regulator input?

    It is much kinder to the transformer to use full wave rectification. If using a reservoir capacitor, the voltage will not be much higher than half wave rectification. The 12V relays can run on rectified AC with no capacitor. Put a suitable resistor in series with each relay and include a...
  2. duke37

    Insufficient Power on my Load

    R2 and R3 are connected in series, one resistor can do the job.
  3. duke37

    Insufficient Power on my Load

    I do not see 4W anywhere. U1 is a regulator giving a constant voltage output so long as the input voltage is a couple of voltage above the output. You can calculate the output voltage since there will be 1.25V across R5. There will be negligible current going into the ADJ pin. There is no...
  4. duke37

    Unknown item

    That looks like a bridge rectifier with three of the connections broken off. It would help if we knew where it came from. I guess that it is a 730V, 1A bridge. You will need to look up the rating and get one to suit from almost any electronics store.
  5. duke37

    How do I reduce the speed of a 12v childrens car

    Is the device an LVDT? , linear variable differential transformer. These have two coils which have variable coupling depending on the positon of a core. They need an oscillator to drive them and a phase locked detector to obtain the output.
  6. duke37

    Low voltage indicator lamp of 110vac circuit

    Normally, a pair of diodes in inverse parallel is used so that each diode protects the other ffrom excessive voltage.
  7. duke37

    Low voltage indicator lamp of 110vac circuit

    You could put a current transformer at the switch driving a led, so indicating passing current. It may be possible to monitor the current and detect if the pump is stalled. The only best way is to measure pressure.
  8. duke37

    Hello Fellow Boardronauts + Question re: replacement power supply variance

    Connecting a 4V AC power supply in parallel with a 6V AC supply will cause failure since the 6V supply will feed into the 4V supply. Putting the supplies in series will give 2V or 10V depending on the polarity. The maximum current permitted is that of the weakest supply.
  9. duke37

    Electrolytic Capacitors With Higher Stamped Value

    With a 4V capacitor as shown, measure the current going into it from two 1.5V cells in series. Capacitor measurements are done with AC for smaller values but use a charge time for large electrolytics. See how your meter does it. If the capacitor is leaky, the voltages could be low, generating...
  10. duke37

    Electrolytic Capacitors With Higher Stamped Value

    If the capacitor is leaking, then it will take longer to charge and appear like a larger capacitance. Measure leakage at rated voltage.
  11. duke37

    Milwaukee Super Sawzall Intermittent Stopping

    No idea what gubbins you have but if it has a universal motor then I would think that the brushes are shot and making intermittent contact with the commutator.
  12. duke37

    Can you extend the leads on a fluorescent ballast (blown ballast?)

    The old ballasts were nothing more than an inductance. I have used the wire for other purposes. The lead length should be irrelevant I have no knowledge on modern electronic ballasts.
  13. duke37

    help rewiring a electric fan switch to a alarm clock?

    If your fan needs mains voltage, I suggest that you delay implementation until you have more expertise. A small low voltage DC fan should be safe to play with and can be switched with a transistor.
  14. duke37

    Marantz 2015 Receiver Distortion

    Measure the voltage at the centre of the output emitter resistors.or the positive of the large output capacitor. Plug in a speaker and see if it changes. Does plugging in one speaker affect the other channel, using headphones as a monitor?
  15. duke37

    REPAIR HELP: Philips Speaker System 2.1 SPA2360/17

    Did you cut the lead to L1? or did it fuse. If the latter, then there is something very wrong elsewhere. You could try replacing it with a plain wire.
  16. duke37

    Battery charger Diode question

    Draw a digagram of what you think the circuit is like. Is the input three phase? Where is the output conected? The plates are part of the circuit and presumably be insulated from the case. I have never used diodes such as you show but the red ring probably means something. I have used stud...
  17. duke37

    Circuit symbols Identification

    The screen may be connected at both ends and may be one ended only. Sometimes the neutral signal wire is connected to the screen. In your picture at the bottom right show clearly three connections, others show only two. Someone has spent quite a time on getting the earthing done properly to...
  18. duke37

    Battery charger Diode question

    Four diodes are used in a single phase circuit. Six diodes are used in a three phase circuit. Which have you got? If you are unsure of the correct connections, then work out the circuit diagram and replace the diodes with something cheap (1N400x) to get the right polarity, then when it works...
  19. duke37

    Screwdrivers?

    Screwdrivers can be reground and soft ones may need to be ground often. The insulation will not interfere with anything. You could get a set of driver bits for various screws including cross bits and Phillips. A set of watchmaker screwdrivers will often come in handy. I use a 'magic' (neon)...
  20. duke37

    Circuit symbols Identification

    The symbol you show looks very like the symbol for 'shielded wire or coaxial cable'. Are you sure that the cable has no shield? Post a picture of the appropriate cable with connection.
Top