Just a simple host board for making (playing with) Constant-Current drivers easier & more fun. I didn’t list any code for the Picaxe 60Hz PWM that may be used to build a variable current source as most of y’all already know how to do that.
If anybody uses this stuff to make a programmable battery charger, please share. I’ll get around to that eventually, but I’m retired so I don’t do anything on a schedule. It’s been too rainy & windy to fish, so that’s the reason this little project came about.
1W Version:
10PCS 350mA 1W LED Driver PWM Light Dimmer DC-DC 5-35V Step Down Module
https://www.ebay.com/itm/10PCS-350mA-1W-LED-Driver-PWM-Light-Dimmer-DC-DC-5-35V-Step-Down-Module/221925032959?_trkparms=aid=888007&algo=DISC.MBE&ao=1&asc=50526&meid=9bb990bec4904a8c88e98e8c70bd05b6&pid=100009&rk=1&rkt=1&sd=331898220748&itm=221925032959&_trksid=p2047675.c100009.m1982
3W Version:
3W 5-35V LED Driver 700mA PWM Dimming DC to DC Step-down Constant Current
https://www.ebay.com/itm/3W-5-35V-LED-Driver-700mA-PWM-Dimming-DC-to-DC-Step-down-Constant-Current/112688757224?hash=item1a3cc5f9e8:g:tjMAAOSwbihaOjJ1
XLSEMI XL4001 datasheet http://www.xlsemi.com/datasheet/XL4001 datasheet.pdf
While the ebay boards do work just fine for holding the 350mA constant current needed by 1W hi-intensity LEDs, there were a few things I didn’t like:
01 No terminal strips or mounting holes.
02 The PWM input is a little stinky: Using a PWM source, found that the board would supply current in excess of
the 350mA required by the 1W LEDs when PWM was beyond 75%.
03 The PWM input does not work well with hi-frequency PWM. Seems to work best with ~60Hz. However, this works
OK as a dimmer or variable current source. Not a big deal.
The host board doesn’t change a whole lot, just makes it easier to work with:
01 Added terminal strip & mounting holes. Also added 4 2-pin IDC connectors so LEDs can be quickly connected or
removed. Note that since the connectors are in series, a missing LED must have a jumper on it’s connector.
Note also that the terminal strip LED connection should not be used when using the IDC connectors as this would
create a parallel circuit for the current source (would this ever be useful?).
02 Added an open-collector transistor in front of the PWM input. This flips the logic to Hi=ON & Lo=OFF & also lets
the PWM be varied from 0 to 100% without exceeding the 350mA limit for 1W LEDs (so I don’t accidently zap the
connected load when playing with PWM from the Picaxe). A light dimmer shouldn’t burn out the bulbs at full-on!
Don’t forget to use 60Hz PWM frequency.
Considerations:
The board would make an excellent current source for a programmable battery charger when coupled to a Picaxe.
Of course, the Picaxe would need to read the battery voltage & charging current. Need to do this after I get done
with the lighting & alarm applications. Could wind a little shunt & hang it on one of the IDC connectors to pick up
current. A variable current source is handy for controlling pressure or tension, so keep that in mind. Could make a
little dancer roll for keeping line tension constant on my reel winder. Could also be used as a temperature
controller but I’ll need to do a simple PID proc (as used on kayak nav-lock).
If anybody uses this stuff to make a programmable battery charger, please share. I’ll get around to that eventually, but I’m retired so I don’t do anything on a schedule. It’s been too rainy & windy to fish, so that’s the reason this little project came about.
1W Version:
10PCS 350mA 1W LED Driver PWM Light Dimmer DC-DC 5-35V Step Down Module
https://www.ebay.com/itm/10PCS-350mA-1W-LED-Driver-PWM-Light-Dimmer-DC-DC-5-35V-Step-Down-Module/221925032959?_trkparms=aid=888007&algo=DISC.MBE&ao=1&asc=50526&meid=9bb990bec4904a8c88e98e8c70bd05b6&pid=100009&rk=1&rkt=1&sd=331898220748&itm=221925032959&_trksid=p2047675.c100009.m1982
3W Version:
3W 5-35V LED Driver 700mA PWM Dimming DC to DC Step-down Constant Current
https://www.ebay.com/itm/3W-5-35V-LED-Driver-700mA-PWM-Dimming-DC-to-DC-Step-down-Constant-Current/112688757224?hash=item1a3cc5f9e8:g:tjMAAOSwbihaOjJ1
XLSEMI XL4001 datasheet http://www.xlsemi.com/datasheet/XL4001 datasheet.pdf
While the ebay boards do work just fine for holding the 350mA constant current needed by 1W hi-intensity LEDs, there were a few things I didn’t like:
01 No terminal strips or mounting holes.
02 The PWM input is a little stinky: Using a PWM source, found that the board would supply current in excess of
the 350mA required by the 1W LEDs when PWM was beyond 75%.
03 The PWM input does not work well with hi-frequency PWM. Seems to work best with ~60Hz. However, this works
OK as a dimmer or variable current source. Not a big deal.
The host board doesn’t change a whole lot, just makes it easier to work with:
01 Added terminal strip & mounting holes. Also added 4 2-pin IDC connectors so LEDs can be quickly connected or
removed. Note that since the connectors are in series, a missing LED must have a jumper on it’s connector.
Note also that the terminal strip LED connection should not be used when using the IDC connectors as this would
create a parallel circuit for the current source (would this ever be useful?).
02 Added an open-collector transistor in front of the PWM input. This flips the logic to Hi=ON & Lo=OFF & also lets
the PWM be varied from 0 to 100% without exceeding the 350mA limit for 1W LEDs (so I don’t accidently zap the
connected load when playing with PWM from the Picaxe). A light dimmer shouldn’t burn out the bulbs at full-on!
Don’t forget to use 60Hz PWM frequency.
Considerations:
The board would make an excellent current source for a programmable battery charger when coupled to a Picaxe.
Of course, the Picaxe would need to read the battery voltage & charging current. Need to do this after I get done
with the lighting & alarm applications. Could wind a little shunt & hang it on one of the IDC connectors to pick up
current. A variable current source is handy for controlling pressure or tension, so keep that in mind. Could make a
little dancer roll for keeping line tension constant on my reel winder. Could also be used as a temperature
controller but I’ll need to do a simple PID proc (as used on kayak nav-lock).
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