OPEN SOURCE: "CC-Boost" - 2.4 Amp boost driver - RC1

[Mattronium]

I would gladly donate a little if I could use pp. Also, I don't know if this has already been answered but how would we go about making a >500mA driver? Would it be safe just to change the resistors?

EDIT: Also, does the 10x10mm board posted on the first page work fine also?

 

[The Lightning Stalker]

PM Scent

 

[rhd]

I would gladly donate a little if I could use pp. Also, I don't know if this has already been answered but how would we go about making a >500mA driver? Would it be safe just to change the resistors?

EDIT: Also, does the 10x10mm board posted on the first page work fine also?

I'm not on my PC right now, but if someone glances at the schematic, I may have left the current calculations inside in text. You should do the math to be sure, but changing the sense resistor would be the best way to create a low current driver without sacrificing enough power getting to the ZXCT.

Nope, I've removed the 10x10

 

[crazyspaz]

got some chips sent out to LS. Hopefully he just got a bum batch, and all is fine...hopefully.

 

[The Lightning Stalker]

I have discovered yet another problem. This
time it's DigiKey's fault. The "22µF" 0805
capacitors they sold me are actually 14µF!
That is a full 36% under tolerance! I think
they may have been switched with some 14
or 15µF units. I did not even think to check
until just now. So that could be the whole
problem. DigiKey should be sending some
new ones along in the next couple days.

 

[The Lightning Stalker]

I just measured them again, and now they
are 17µF? I don't know what is going on.
Still under tolerance, though

 

[ARG]

I just measured them again, and now they
are 17µF? I don't know what is going on.
Still under tolerance, though

What is the tolerance you have?

Is it possible you're not leaving them on the meter long enough to get a good read? Larger caps take longer to get a solid reading from with some instruments.

Edit: Also, what are you using to measure the capacitance?

 

[RGB]

I have discovered yet another problem. This
time it's DigiKey's fault. The "22µF" 0805
capacitors they sold me are actually 14µF!
That is a full 36% under tolerance! I think
they may have been switched with some 14
or 15µF units. I did not even think to check
until just now. So that could be the whole
problem. DigiKey should be sending some
new ones along in the next couple days.

Ceramic capacitors are voltage dependent! This means that it might not be any fault at all!
Ceramic capacitor - Wikipedia, the free encyclopedia

 

[The Lightning Stalker]

What is the tolerance you have?

20%

Is it possible you're not leaving them on the meter long enough to get a good read? Larger caps take longer to get a solid reading from with some instruments.

I tried leaving a new one on the meter. After
several minutes, the capacitance did rise, but
never broke the 15µF mark.

Edit: Also, what are you using to measure the capacitance?

The meter is an Extech 380193 LCR meater.

To explain the 17µF reading, the ones that
measured 17µF had been soldered in and
used. The fresh ones are still measuring
14µF. I also overvolted those ones, so
that could account for some of the
discrepancy.

 

[rhd]

Sure

I just checked and my diodes are rated for 5A - but you probably want the full 10A range tested?

I built you a 30A test load from these:
FFPF30UA60S Fairchild Semiconductor | FFPF30UA60SFS-ND | DigiKey



Well - it's just three of them on a copper heatsink, but I think it will do.

I didn't have an appropriate resistor though. Do you have a spare 0.01 ohm resistor? Or a DMM that can handle 10A in current mode? If not, I'll order a resistor.

 

[The Lightning Stalker]

Do the ZXCTs have a maximum gain? I've
been experiencing some problems with some
of my boards that could be caused by
setting the gain above some limit. There
doesn't seem to be one specified in the
datasheet.

 

[rhd]

Do the ZXCTs have a maximum gain? I've
been experiencing some problems with some
of my boards that could be caused by
setting the gain above some limit. There
doesn't seem to be one specified in the
datasheet.

Sort of. The 1009s need at least a 50mV drop across the sense resistor, and have a max too. Forget what it is, but its 150 or 250 or 500mV, just check the datasheet. It's in there.

 

[ARG]

I built you a 30A test load from these:
FFPF30UA60S Fairchild Semiconductor | FFPF30UA60SFS-ND | DigiKey



Well - it's just three of them on a copper heatsink, but I think it will do.

I didn't have an appropriate resistor though. Do you have a spare 0.01 ohm resistor? Or a DMM that can handle 10A in current mode? If not, I'll order a resistor.

Awesome! Thanks!

I've got a Fluke DMM that can handle 10A, should be fine

 

[rhd]

Awesome! Thanks!

I've got a Fluke DMM that can handle 10A, should be fine

That should be fine. I assume the leads can handle the current?

I have a chinese DMM that "can handle 20A", and the leads melted when I tried to test this driver at 9A

 

[ARG]

I've got some 14ga test leads, should have more than enough ampacity.

 

[djQUAN]

Build a dedicated ammeter using a DPM or analog meter. I never use the built in amps function in a multimeter since I usually forget to put back the probes to the voltage jacks then when I measure the wall outlet voltage, Bang.