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  1. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Is it for sure a 50k potentiometer? Do you know that for sure? I have the module on order, Now I need to order the potentiometer.. What should I do about the smoothing capacitor? What value is the correct size? 6800uF? Bigger? Smaller? I am going to order one either way, so the price is...
  2. TheChad

    Koford (Slot Car) Bench Power Supply Project

    The potentiometer that is on the power supply right now is http://www.mouser.com/Search/m_ProductDetail.aspx?Alpha-Taiwan%2fRV170SF-10-15R1-B1K%2f&qs=sGAEpiMZZMsb7Mk3aR4n05bmgoB3qUuV I was going to install the 5k version of the same potentiometer to give me finer control of the voltage... They...
  3. TheChad

    Koford (Slot Car) Bench Power Supply Project

    I have a module on order... So I will know for sure once I get it... But from the pictures, it looks like 503 (50,000) ohm.. That seems like a whole lot... But I checked and my potentiometer is available in a 50k ohm... I have to order another potentiometer no matter what... I may just...
  4. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Thanks soo much for the reply/information! At this point with the use of that module, changing to a switch mode is a no brainier! Now my only concern is the built in potentiometer... -TheChad
  5. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Thank you again for your information... I don't know what other information to provide about the load.... All this power supply is used for is running electric motors... The MAX Amps I will likely ever pull is 5A and that would be at 4+ volts... These motors pull their max amps at 4v, past...
  6. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Sounds simple enough, actually seems easier than messing with the regulators at all..... Really I'm only switching out 1 component, the regulators for the Switch mode... So this seems like the new plan... So, does the potentiometer rating matter? The potentiometer in the power supply case...
  7. TheChad

    Koford (Slot Car) Bench Power Supply Project

    So I could keep the 12.6v 8A transformer..? But it only works at a set voltage? whatever the potentiometer on the board is set to? I need to be able to adjust it with the potentiometer on the front of the power supply.. (I could unsolder the potentiometer on the board and solder in jumper...
  8. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Not currently, but I will get some resistors and install them. I just wanted to make sure the 1 regulator wasn't getting hot because it was faulty or something.. I would *think* typically the FIRST regulator in the group would get the hottest not the last if current sharing was a problem...
  9. TheChad

    Koford (Slot Car) Bench Power Supply Project

    That looks simple enough to install..... What else would I need to make that work? How would that be adapted/installed in my power supply? -TheChad
  10. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Sometimes what you say has been contradictive to me... You said the regulators "DON'T" run away, but then you said not to run them in parallel unless I make sure they are balancing the load.. So that to me seems like a contradiction. I also am not sure you are fully reading my posts... I...
  11. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Thanks for the sarcasm. We all KNEW they would get warm/hot... That's kind of what started everything.... So the problem now is that 1 is hotter then the other 2... I am still going to get a real temp once I find my infrared temp gun.. But the LM350 is rated up to 150-Degree's Celsius...
  12. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Okay.. I was digging threw my old Slot Car stuff, and FOUND the capacitor I took out.... It is a 33000uF... I replaced a 33000uF with a 4700uf, I think I did this because the 33,000uF is only rated to 10V, but I'm not sure why I did a 4700uF, unless I thought it was 3300uF not 33000uF.... So...
  13. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Okay, I just ran a slightly hotter motor than I was testing with before. I was using a motor that barley drew .5A, now I tested a motor that drew 1.25A. The regulators got slightly to the warm side of luke warm, except 1, which got hot enough that I didn't want to keep my finger there for...
  14. TheChad

    Koford (Slot Car) Bench Power Supply Project

    I will likely NEVER run minimum voltage at maximum current.... I'm not even sure how I could pull that much current at low voltage.... Typically my 'Fast" motors pull about ~4A @ 4v. Slower motors will pull 1.5-3A @ 4v. Typically if I am breaking in a motor I will run it from 3v-5v for ~10...
  15. TheChad

    Koford (Slot Car) Bench Power Supply Project

    I appreciate all the great information... What you suggest makes since, however this is a bench power supply, not a power supply that runs constantly or for long periods.. The longest I would probably ever have it turned on under load is maybe 20 minutes... I can't stress enough how much I...
  16. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Well up to about 6 amps. That's kind of what I'm doing here... The basic design was already done, as it was a store bought power supply. However it did not meet my needs as it didn't have enough power. So I modified it, perhaps blindly, by adding a larger transformer. Now I am looking...
  17. TheChad

    Koford (Slot Car) Bench Power Supply Project

    I can't use a single regulator, 5A isn't big enough, I could use 2 5A regulators.. I could install them all to their own heat sink and put them further apart.... But it was mentioned earlier that there is a reason for them to be mounted close and to the same heat sink, to prevent any of them...
  18. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Great! One less component to worry about! I was doing some more testing today and it looks like the voltage jumping around may be due to a loose connection on the potentiometer... One of the colder tabs is loose (Which is why I am ordering a new one), and I put a drop of solder on it to hold...
  19. TheChad

    Koford (Slot Car) Bench Power Supply Project

    With that information, then my 4700 uF capacitor is too small.. Colin said earlier that I'm at about 5.7a DC after rectification, so I should have a 5800uF capacitor? Okay, I went and picked up a 100uF capacitor and a 1MegOhm resistor... Where should they be installed? Directly after the...
  20. TheChad

    Koford (Slot Car) Bench Power Supply Project

    Looking at this website: http://www.learningaboutelectronics.com/Articles/How-to-build-a-DC-power-supply.php It basically outlines how to build my power supply. It shows the use of 100uF capacitor in the location we are talking about.. Does that sound about right? Anyone? Thanks! -TheChad
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