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  1. Minder

    Help required to identify circuit board

    The IC part No's are on each device, in extreme cases, a OEM/manuf will use proprietary Numbering. Post a couple and it should be evident if it is so. M.
  2. Minder

    Help required to identify circuit board

    List the part No of the IC's used and most likely it could identify the end use of the boards. M.
  3. Minder

    7805 regulator capacitors

    You actually only need .1uf on the out pin if the rest of the circuit is close to it, and the rest of circuit fed has capacitive smoothing. The recommended on the input is 0.3Uf. M.
  4. Minder

    New boy on the forum...

    I remember mine in the late '40s, it used a actual cats whisker, i.e. Galena crystal.! In my early ,20's spent Time in Libya with the Royal Signals, we also had a Ham radio license and at that time there were only two Ham call signs in Libya, that we knew of, Once on the air we were swamped with...
  5. Minder

    7805 regulator capacitors

    Sorry, misprint, should be 78L05. Tantalum in this application should be OK. Solid Aluminium also, both typically smaller than the typical electolytic. M.
  6. Minder

    7805 regulator capacitors

    See the ST app note on the IC, I always use the recommended .33uf on the input, and a .1uf on the output, if the circuit being fed is not near to the regulator, I add a 15uf to 20uf across the ,1uf. For 300ma you could use the 79L05 series. M.
  7. Minder

    finding 4 pin connectors for own wires

    Search the Digikey on-line catalogue, there is pages and pages of selections. M.
  8. Minder

    24 Volt DC Transformer to AC mod ?

    That one should be fine. M.
  9. Minder

    24 Volt DC Transformer to AC mod ?

    If this is a Wall-Wart older type, it could have a linear P.S. transformer with the typical bridge and capacitors on the output, if so, the voltage on these are typically rated at the stated load current, i.e. open circuit the voltage is higher, If this is the case, Just use the transformer...
  10. Minder

    powering a cordless drill with PSU in drill press DIY build

    What many have done is use an ex treadmill DC motor, this runs direct off of 120vac in N.A. There is two types of popular T.M. boards, the MC60 which is the simpler SCR bridge version or the PWM MC2100 version, with the latter version, a control board is needed. There is some out there designed...
  11. Minder

    I also need help finding replacement transformer for oven control board-

    Presumably there should be a connection to the neutral pin! Do you get continuity from one of the fuse terminals to this neutral? What is the one 'mated' to the supply pin M.
  12. Minder

    I also need help finding replacement transformer for oven control board-

    You should be able to locate an equivalent fuse, checking the primary pins will show open with the fuse blown, jumper the fuse and re-check continuity. Also if you do identify it and connect 120vac while out of circuit, you may be able to identify the secondary voltage(s), In order to look for a...
  13. Minder

    I also need help finding replacement transformer for oven control board-

    It appears that you may have blown what appears to be the thermal fuse on the outside of the transformer winding, It my be worth a check as if it is, it should be easy to fix. M.
  14. Minder

    Jumper wire

    Most jumpers on ebay (male-female) are intended for bread board. M.
  15. Minder

    restoring old garage door opener-receiver/transmitter

    Then the 433Mhz ebay version could be used to close the contact that is apparently done by the P.B.! M.
  16. Minder

    Silent electric motor to drive turntable.

    The only thing I can see might happen with a stepper principle, especially at low RPM, is 'cogging' also seen on (multi-pole) BLDC motors at low RPM when used with no PID feedback. M.
  17. Minder

    Silent electric motor to drive turntable.

    If using the 1:1 ratio like that, you may need quite a bit of power to rotate 200lbs and also stop it precisely at the 90° point. If it has a vertical shaft and bearing below the table, one method to reduce friction is to place a large ball bearing below at the bottom of the shaft to support it...
  18. Minder

    Silent electric motor to drive turntable.

    A bit of an extreme to a 200lb T.T. but as a comparison the old LP record tables were extremely quiet and worked by using a synchronous AC motor and belt drive. You may achieve this using a timing belt and pulleys for drive and reduction. DC or BLDC servo motors are extremely quiet. M.
  19. Minder

    Silent electric motor to drive turntable.

    You would have to calculate the torque required and then decide if gearing is warranted, one of the quieter means of gearing is using a planetary G.B. Most DC motors and BLDC are extremely quiet, especially if ran at low RPM with gearing. Rotating 200lbs is probably going to be difficult to...
  20. Minder

    restoring old garage door opener-receiver/transmitter

    Do you have, or can you obtain the system schematic? Heathkit used to be good at providing info. M.
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