First DIY Build - Easy Questions

[bobo99]

I will be using a BDR-S06J, and a V5 flex drive.

1) I couldn't find 1n4001 diodes, I only have 3 1n4002 and diodes and 3 1n4006 diodes and a 1.3 ohm resistor. Will the 3 1n4002 be ok to use to build the dummy load?
(data sheet: http://www.diodes.com/datasheets/ds28002.pdf )

2) The dummy load created will be like this : http://www.rog8811.com/test load01.jpg and the current will be measured across the output of the V5 Flex?

3) How much heat sinking will I be need to provide for the V5 flex? Just some thermal tape, and wedged near the heatsink?

I wouldn't have issues reading this off the forums, however some of the more specific items are difficult to find.

If you have any other recommendations for my first build, that would be appreciated.


Thanks!

 

[bobo99]

Ok so some experimentation with the dioides... I put 4x1n4002 and 3x1n4006 diodes in series, and the 1.3 ohm resistor. I hooked this up to a 5V power supply , and then measured the voltage drop across the series of diodes and resistor, and got... just shy of 5 V (not shown in picture, couldn't get the contacts to stick as I took the picture)...


Is this adequate for a dummy load, DTR mentioned it should be closer to 6V, however I can't drop 6V, if my power source is 5V... I think.

 

[rhd]

I never measure current the way others here do. I know the "norm" is to measure the V across the resistor on your test load, and just swap units to A.

I much prefer to have a DMM in series with the test load, and use current mode on the meter.

However, if you're doing the former (as most people here do), you need that resistor to be bang on 1 ohm, not 1.3ohm. Otherwise the simple unit-swap from V reading to A doesn't work. Ohm's law is the key here.

So either use a 1 ohm resistor, or measure current in the current measuring mode with your meter in series with the test load.

 

[bobo99]

Ok I think I'm ready to test this...

Was extremely painful to bridge the resistors underneath the pot... so used a paperclip and laid solder across that...


Instead of using a battery, can I plug in the V5flex into the 5V power source that I have built?


I took out the 1.3ohm resistor and measure directly in series like you mentioned and got a reading of what looks like 75mA, I'll be honest, this analogue ameter sucks..



Thanks!

 

[bobo99]

So I plugged in the flex directly into the 5V source.

It runs through the 6 diodes, and directly through the ammeter.

It reads... 50mA? I think?

However whenever I turn the pot, nothing changes. While I was soldering the pins I may have damaged the pot...

The ammeter is set to the 500mA setting...

 

[bobo99]

Figured it out!

First- Went out and bought a digital multi meter, this analogue business was painful. (turns out the one was DOA, but anyways)

Now that I have an accurate reading of the current, I have discovered that the custom built 5V power supply can only push out about 60mA, through the driver. I hooked up another wall wart , and tadaa, its now set .5A. perfect.


Edit: OK not so tada.. Got back from a long day of school, and had my power source that was connected to the flex drive set to 7.5V. I turned it on, and after about 5 seconds I realized and quickly turned it off.
Needless to say that I think that did it for the flex drive. It puts out about 50mA and fluctuates wildly from 30mA to 80 and then down to zero (it was set to 500mA last night), and gets intensely hot after a few seconds of use.
Anyone have a flex drive to sell?

 

[Wolfman29]

Good stuff, and good job!

Just some friendly advice so you don't get -rep though - try to keep double/triple posting to a minimum. The general rule is always just edit your last post unless it has been 48 hours or more since your last post AND you have extra information to add.