Awhile back, a friend gave me some hardware when he was moving. Half the stuff, he didn't even know what it was. (He's a tinkerer). One of the thing he gave me looked like a CCD system, but of a medical nature. Basically, several boxes with two cameras with large IR illuminators. Turns out it's some sort of motion analyser (Elite BTS) used to analyze people's gate with various illnesses. It's an older version and couldn't find any docs. I was thinking of making new IR augmented fog lights for my car as one of the stockers was ruined due to the chrome-ish layer coming off and the heat from the bulb damaging the housing as it wasn't reflected. Why IR in the car? Well I have cameras in the car so I was thinking something akin to night vision through the monitor. Not really practical, but I digress. Anyway, each illuminator has 120 IR leds. Hard to follow the traces, but there's 20 15ohm 1/4watt resistors. So I'm guessing it's 20 runs of 6 leds. There's only two things of note on the board. A HCF4538BE (Dual Monostable Multivibrator) and a IR350 transistor. Leading up to the led side is 25 220uf 25v capacitors. I'm guessing this is to smooth the output when they turn on? There's three leads from the camera. I'm guessing +,- and control. So am I on the right track? I'm guessing the monostable pulses them on an off. Says 100hz on the side of the camera. I know I should be able to calculate it with series-parrallel, but I can't wrap my head around it. Any guidance would be appreciated.
Guessing a forward voltage of 1.6V, a 12V supply with 15R, 6 leds would give 160mA, which isn't OTT if they're pulsed. The 20 runs will draw 3.2A, but not continuous if they're doing freeze-frame. Do you know if it is 12V? All them caps seems odd, could they discharge through the transistor & leds on switching, recharge in the off period, to give a low-impedance, high ripple-current-tolerant power supply? Like sticking a 1F in a car audio?
Just the man I was hoping would reply I don't know if it's 12v for sure. Most cameras are usually 24v or 12v. I messed up on the transistor number, it's a IRF530. Don't really know much about Mosfet transistors. Hard to remove the "cap" board, but it looks like the monostable goes to the first pin on the mosfet. The caps connect between traces that come from the second and third pins. The cathode goes to the 2nd pin, the anode to the 3rd.
Here's a link to a larger pic of the board. update I guess the way the system works is the patient has reflective material attached to key locations, the multiple cameras strobe to record the position in 3d space. They connect to these boxes which do the analyzing. If I could get it to work and the software, it might be worth keeping just for that. But I believe I only have two of the cameras, so probably not doable. The cameras have 3 connectors on them. Synch, Flash & Video out. So yeah, they are for pulsing. I suppose if I can't figure it out, I could always change the resistors out. That wouldn't be that much work. Though I'd like to get em to work without modding if possible.
My favourite MOSFET. Cheap, 14A and low on-resistance. But it doesn't make much sense. First pin is gate, so when it's switched on the caps will be shorted through the MOSFET drain & source, pins 2 & 3, (on-resistance around 0.11 ohm). Seems a bit brutal.
I might just try to apply 12volts to it and to the control and see what happens (using a camera). Swapping out the resistors and loosing the board is an option too. Thanks again.
