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  1. Minder

    Controversial schematic symbol

    I believe what you are referring to is non-polarized capacitors, IOW they work with both polarity. One of the main reasons for this difference in marking is in HF or radio circuitry where the capacitors are use for de-coupling. The curved bar end goes to ground connection, this connects to the...
  2. Minder

    Testing Salvaged Motors

    With the likes of a PWM controller etc, the initial current can be controlled/limited by gradually bringing the motor up to speed. M.
  3. Minder

    Testing Salvaged Motors

    The absolute maximum current of a DC brushed motor is when stationary and when full voltage is applied, which should be very brief if the motor is allowed to come up to rated speed within the continuous current range. You could find this value by taking a resistance measure of the armature. To...
  4. Minder

    Testing Salvaged Motors

    Depends on the motor, e.g. stepper motors use the same (rated) current whether at zero or high rpm. DC motors the current depends on load and is also maximum at switch on, if/when full voltage is applied. They have continuous rated current (torque) and peak current, the latter should only be...
  5. Minder

    Motor Stronger than Powersupply?

    If you are going to stall the motor, the PWM allowable current limit is to have to be either the rated continuous stall torque current of the motor rather than the peak allowable current, or the limit of the P.S. M.
  6. Minder

    Vacation

    We'll keep your parking spot open!;) M.
  7. Minder

    Motor Stronger than Powersupply?

    That is most likely the stall at maximum load or when powered at full voltage. If you have any kind of PWM or similar control, the current can be limited. Do not turn on the power with the PWM set to max. IOW ensure o rpm at switch on. Also a suitable fuse should be used in case of accidental...
  8. Minder

    Homemade Multi-Drill

    Personally I would not use those or any SMPS (switch mode) power supplies for motors. It may cost a little more to just use a transformer and bridge rectifier, but only entails two components which are far more rugged for this application. M.
  9. Minder

    An amateur requests help with motors

    Although the Smart Relay is digital (boolean logic) programming.;) M.
  10. Minder

    An amateur requests help with motors

    You can also program a sequencer in the Smart Relay. You also get a bunch of timers etc, if needed. M.
  11. Minder

    Capacitor for 240v 1/4 hp vintage lathe.

    Why not continue the same thread? https://www.electronicspoint.com/threads/capacitor-for-240v-1-4-hp-vintage-lathe.288938/page-2#post-1770647 M.
  12. Minder

    Identifying circuit component (schematic)

    It means the negetive side of each of the supplies are common (connected) to each other, one connection. However way you want to do it, either by printed circuit or hardwired.. M.
  13. Minder

    Identifying circuit component (schematic)

    Simply means these point to the power source 12v to 50v 8a and 9v to 18v, whatever the source maybe. The commons of the supply are connected together. Bottom of D2 & Q1 & C2. M.
  14. Minder

    Carpet Cleaner Circuit / Transformer

    Depends on what is between the motor and power supply, if the motor checks out then the next thing would be the 15v. After that, any controller between the 15v and motor. M.
  15. Minder

    Carpet Cleaner Circuit / Transformer

    If you are sure the motor is low voltage and if it is DC, a test could be used on it using an automotive battery . Disconnect the motor first. Also check the 15vac with a meter. M.
  16. Minder

    Capacitor for 240v 1/4 hp vintage lathe.

    You could try the values suggested, if you want to zero in on the correct one, try a value and monitor the current, if close to the motor rated plate current it should be OK, one way is to obtain 3 or 4 of low value and place them in parallel one at a time and test current. It is not super...
  17. Minder

    Capacitor for 240v 1/4 hp vintage lathe.

    One way to check the cap is to remove any belts etc and give it a fast spin at the same time be careful turn the power on, If the cap is the problem, it normally would run in either direction, which ever way you spin it. If replaceing the cap, ensure you get motor start/run rated version and...
  18. Minder

    An amateur requests help with motors

    I would think small DC motors with high ratio gear boxes, this also give a measure of safety with isolated DC via suitable 230v to 12vdc transformers together with a suitable bridge rectifier. You will need to set up some kind of relay sequencer, or use a Smart Relay where the logic is...
  19. Minder

    12V/5A from 19.5V/4.6A laptop charger

    Although this only generally applies with a AC version, the DC should be the same when energized. This is why the AC version only has the edge at switch on, current is high until the inrush and the armature has moved over and inductive reactance takes over, apart from this the DC has the edge. M.
  20. Minder

    Solenoid amperes ???

    If it is a DC coil measure the resistance and it will tell you, (Ohms Law!) the current for a typical DC sol of that size is around 1a to 1.5a If it is very low resistance then it is the AC variety. Also if switching it electronically, you will need a BEMF diode across the coil, in4002,,-7 etc M.
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