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  1. #16
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    Watson,

    Thanks for the swift feedback, I'll check my motor but suspect your right.
    Dragonfly
    No-one suspects the dragonfly!

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  3. #17
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    Sep 2007
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    Dear Chaps,

    When one of you are able to, could you please measure the installed resistances across the following two Resistors:

    1) The 1/2w 1000ohm (ie. the unit at the right end of the little group of three...)
    2) The 1/2w 100ohm (ie. the unit at the bottom right corner of the board...)

    I ask the question because I'm a little miffed at the lack of speed-change in the upper 2/3 of the main Pot's range. I measured the Resistors before I put them in, and they were all spot-on, but now the two said components are reading lower on the board...

    Now the thing is - once installed, the measured resistances of Resistors can be decreased from their rated value by parallel circuitry, so this could be why I'm getting the lower-than-rated resistances. But then again, I might have also "cooked" them during installation.... If I can compare my measurements with somebody else's, and there's significant difference, it will most likely be due to such "cooking", and this could then be the cause of the lack of variation in the upper 2/3rds of my main Pot's range...

    Many Thanks in advance,
    Batpig.

  4. #18
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    May 2004
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    Melbourne, Australia
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    523

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    Batpig,

    Top job with the construction

    You might like to check the "taper" of the pot. They may have given you a "log" or "antilog" rather than a "linear" pot.

  5. #19
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    just in case there's a stuff up.
    'Tother thing, were the items you tested it on fitted with internal speed controllers??
    If so, they are looking for a sine wave to control, not the half-wave, spiky fronted waveform this kit supplies.
    Looking at the circuit those two resistors will certainly measure low as they are across gates/resistor networks and the 47nf capacitor.
    I'll go up to the shed in the morning and have a measure on mine.

  6. #20
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    Batpig,

    Did a quick measure this morning before I left for work. It measured 530~540 ohms.
    I'll have a good look tonight as work has been rather busy. Got home a 1am and left at 6am. Hoping to get off early today.

  7. #21
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    Sep 2007
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    Dear Chaps,
    Quote Originally Posted by chrisp View Post
    You might like to check the "taper" of the pot. They may have given you a "log" or "antilog" rather than a "linear" pot.
    Thanks Chris - I just had a look at the parts list, as well as in the Jaycar Catalogue with the part no. from the list, and both sources say Linear...

    Quote Originally Posted by watson View Post
    'Tother thing, were the items you tested it on fitted with internal speed controllers??
    As a matter of fact Noel, the Recipro was! (But mind you, the Circular wasn't, and I'm pretty sure that the Pot wasn't doing much up in the top 2/3rds for it either. And same I think for the Bed Lamp...)

    Quote Originally Posted by watson View Post
    Looking at the circuit those two resistors will certainly measure low as they are across gates/resistor networks and the 47nf capacitor.
    I'll go up to the shed in the morning and have a measure on mine.
    That's of some comfort to hear. When you can get around to measuring them, that would be great...

    Quote Originally Posted by The Bleeder View Post
    Did a quick measure this morning before I left for work. It measured 530~540 ohms... ...Hoping to get off early today.
    "Oy oy oy..." Not quite low enough, Steve... I might have cooked something by the looks of it. Please have another measure of both Resistors when you can. I'll type up my own readings when I've heard from Noel.

    Best Wishes,
    Batpig.

  8. #22
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    Back down for lunch.
    The 1k resistor measures 510 ohms, and the 100ohm measures 100 ohm.
    Can you "lift" the end of the 1K nearest the SCR and measure again??

  9. #23
    Join Date
    Feb 2004
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    kuranda north qld
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    Smile

    built a dick smith kit years ago , works well and used on drills and sanders 10 amp max , seems to have torque at low revs ! and remember i had some hassel with the instructions ,as usual . but overall a great thing , cheers bob

  10. #24
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    Dear Noel,
    Quote Originally Posted by watson View Post
    The 1k resistor measures 510 ohms, and the 100ohm measures 100 ohm.
    You and Steve are close enough to each other to obviously be in the correct ballpark... Well, I'm measuring just 136 across the 1k resistor, and 92 across the 100 (photos below). You can understand why I'm a bit pessimistic...
    Quote Originally Posted by watson View Post
    Can you "lift" the end of the 1K nearest the SCR and measure again??
    Yes, I guess I could - I should be able to get the board up because it appears that the Heatsink Compound under the Transistor may not be the "setting" type (or it may not yet have copped enough heat to set yet...)

    Noel - when you are able to, might you hook something into yours and just see how much speed change you end up getting out of the upper 2/3rds of the main Pot's range? Later on today I will take some measurements of the Pot's resistance at low, high, and a few points in-between (I have to mow some lawns first...)

    Many Thanks,
    Batpig.

  11. #25
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    Quote Originally Posted by Batpig View Post

    Noel - when you are able to, might you hook something into yours and just see how much speed change you end up getting out of the upper 2/3rds of the main Pot's range? Later on today I will take some measurements of the Pot's resistance at low, high, and a few points in-between (I have to mow some lawns first...)

    Many Thanks,
    Batpig.
    This morning's play:
    Sewing machine type motor.
    Switch in full speed position.......All OK
    Remove power
    Switch In Control Position....Speed control at Maximum
    Apply power.......motor speed has dropped .
    Turning Speed control down.
    No detectable speed change in the top 1/3 of the Pot's Range (by ear only)
    Cogging started with about 1/3 of pot's range still to go.
    Adjusted VR2
    Still cogging in the same position.
    Switched to full power (forgot to turn power off)
    Little puff of smoke from the motor , but still rattling around ok.

    Hope that helps

  12. #26
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    Batpig,

    Did the measurements again. This time with a bit mor care....here goes.

    Across the 1K is 135 ohms

    Across the 100 ohm is 92 ohms

    Across the 1K - 100 oms parrallel is 53 oms.

    This was done with every thing in situ (no power on though)

    Hope that clears everything up.

    Now for the good news ... mine is the same as yours .. no change in speed in the top 1/3 of pot rotation. Took a bit of stuffing around (assemble disassemble) to stop the router cogging.

    Since this is only going to be used for the router (in the table) I can get safely get the router down to around 1/2 speed (it still has good torque at that).

    Oh, the router is a Makita 3612.

    So yes I'm happy but still a little disapointed on the overall speed control. The one from November 1997 was a much better kit. Speed control was fantastic but the only drawback is if you needed full power you had to unplug it from the controller and plug it into a power point.

  13. #27
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    I wonder why there's a difference in our figures?
    All seems to work OK, with plenty of torque at all settings.
    Do you get any change in resistance across the 1k for different positions of the speed control??


  14. #28
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    Noel,

    That is something I didn't measure (Had the pot on max). I'll do some others with the pot on 1/2 and on min.

  15. #29
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    Had a good ol' play this arvo with three different controllers.
    The Silicon Chip Beast........a Kemo MO12 ..also bought from Jaycar..........and the stock standard circuit that I wire up on vero board and stick inside plastic boxes anywhere I need a controller.

    The Kemo is an encapsulated module with two input wires and two output wires and a pre-wired pot.
    Approved for both universal motors and lights, but only 1200VA.
    Runs like a dream....good control.....minimal cogging......a really good unit.

    The Silicon Chip Kit.
    Not really good control.....cogging occurs early in the rotation...not approved for lighting....will handle a goodly amount of current..........plenty of torque at low revs.

    The stock standard circuit..........costs bugger all because of bulk purchase of components over a few years........easy for me to build........a bit of delay in the first 1/3 pot rotation........cogging occurs at low revs but lots of torque........current handling (dunno) never burnt one out.

    So that was the day that was.

    I've attached the stock standard circuit.....not advocating anyone build it.......probably not kosher for RFI..........but my nearest neighbour is over a mile away.

  16. #30
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    Dear Guys,
    Quote Originally Posted by watson View Post
    No detectable speed change in the top 1/3 of the Pot's Range (by ear only)
    Cogging started with about 1/3 of pot's range still to go.
    Yes - same as mine, Noel, on both counts...
    Quote Originally Posted by watson View Post
    Switched to full power (forgot to turn power off)
    Little puff of smoke from the motor , but still rattling around ok.
    Wow! Here to Avoca! That's the longest-range Havoc I think I've just about ever wreaked! (sorry Noel...)

    Quote Originally Posted by The Bleeder View Post
    Across the 1K is 135 ohms
    Across the 100 ohm is 92 ohms...
    ...Now for the good news ... mine is the same as yours .. no change in speed in the top 1/3 of pot rotation.
    Comforting to hear, in a strange sort of way Steve... Sort of like knowing that you didn't stuff up - it was a design fault... (same difference at the end of the day...)

    Quote Originally Posted by The Bleeder View Post
    So yes I'm happy but still a little disapointed on the overall speed control.
    I'd have to say "Same here..." (given that the kit was $65 worth, which is nothing to be sneezed at...)
    Quote Originally Posted by The Bleeder View Post
    The one from November 1997 was a much better kit. Speed control was fantastic but the only drawback is if you needed full power you had to unplug it from the controller and plug it into a power point.
    I could have lived with that for what I wan't to do with it (slow down the Mitre Saw to cut Plaster Cornices...)

    Quote Originally Posted by watson View Post
    Do you get any change in resistance across the 1k for different positions of the speed control??
    No - same reading Noel, whether at Minimum or Maximum setting...

    Quote Originally Posted by watson View Post
    The Kemo is an encapsulated module with two input wires and two output wires and a pre-wired pot.
    Approved for both universal motors and lights, but only 1200VA.
    Runs like a dream....good control.....minimal cogging......a really good unit.
    That would have happily run my 1600w Mitre Saw at the sort of speeds I've got in mind (would need bugger-all speed and power to cut Plaster Cornices...) I've just had a look at the Jaycar website, and they seem to have backed away a bit from the Kemo stuff... I tried the Mitre Saw out tonight with the Jaycar kit in question, and she's not really a happy camper. I'll have another go tomorrow morning during breakfast...

    Best Wishes,
    Batpig.

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