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If you want to improve the spread slightly, lightly rub the lens with a bit of sand paper. It does decrease the efficiency of the lens a bit as you get some uncontrolled scatter, but you'll get slightly better coverage. Looks good btw, wish I had more focus to get on with mine, but doing...

I used a pallet knife and sliced through with a cutting action. IPA seemed to get the remaining bits of silicon off the glass.

Yes, you could do this if you wanted to control all 10 individually. If you don't need to control them individually then connect as many as you can in series based on your supply voltage. Having 10 8-bit PWM channels on a PIC may pose a challenge, options would be to move up to a faster PIC, or...

Don't try to run 10 LEDs in parallel at 7A!! It follows on from the discussion about variances in forward voltage of the LEDs. If you have 10 LEDs in parallel and one draws 700mA at 3.5V and the rest draw 700mA at 3.6V, the one with the lower forward voltage will be overdriven. Eventually it'll...

The connectors will be fine. If you were running higher currents through the connectors and regularly connected/disconnected them under load you'd find the connections would deteriorate quicker than the same current at AC. Another example is when you select relays - the contact material is...

I'd look at something like the 16F628A or 16F88 as a starter. If the 18F architecture suits you better then look at the 18F1320. I'm using the 18F6722, but it's a bit big for your project :fun:

There probably is a compiler somewhere out there. I'd stick with assembly or C though. I favour assembly until you start using the bigger 16/32 bit PICs.

Definitely. It's straightforward to create a clock to do this, but if you are planning on going down this route I would suggest you start playing and buy something like the PICkit2 which is a bargain IMO (http://uk.farnell.com/microchip/pickit2promo/development-programmer-promo-w/dp/9945350). If...

I wouldn't go down the big capacitor route. PWM is much simpler and smaller. If you don't go down the constant current regulator route and just use a simple resistor to limit current then you can simply use the PWM module built into the majority of PICs. If you do use a constant current...

Yes you can, in fact this is what I am doing on my system. Unfortunately I've been really lazy over Christmas as it was my first break from work for almost a year so I didn't get much done, but I'm starting with the PCB design for the controller which will also control everything else on the...

Because 4.5V doesn't get 'pushed through' the LED. It drives the LED at 700mA and the voltage across the LED is whatever the LED needs at 700mA. If you supplied the driver with 24V and only had one LED connected, the driver would still only drive the LED at 700mA and the voltage across the LED...

You can do this - this is often done with standard LEDs. The issue with high power LEDs is that the resistor in most cases will end up wasting so much power that it negates any energy efficiency of the LED! If you tried to drive a 3W white LED from a 5V supply with a resistor, you'd need a 2.2...

Hi SuperColey, The reason as I explained on the other forum (where I'm registered as aptsys), is that LEDs are current mode devices not voltage mode. With a light bulb, you can provide it with a voltage and it's resistance will limit the current through it. With an LED, if you provide it with...

The test setup would be a programmable current source in series with the diode, and a voltage measurement device in parallel with the diode. By controlling the current with a current source, a voltage develops across the diode purely based on the characteristics of the pn junction. You see...

Hi Rabbut, This figure in the datasheet gives an idea of the voltage drop vs. current relationship: The pulse width is set to 300us to reduce thermal effects. Unfortunately the story is the same for most silicon diodes which consist of a PN junction forming a diffusion region in the middle...

No it doesn't matter, you're not 'putting more' current in, you just have more current available - the drivers take what they need to maintain a constant output current.

A standard silicon diode (1N4001 for example) will drop between 0.6V and 1.2V in normal operating conditions. At 700mA (your drive current) it'll be dropping just over 0.9V and wasting almost two thirds of a watt which will stop you driving your LEDs properly as your transformer's output voltage...

An RCD and surge protector will do nothing to protect the circuit as the circuit is isolated from the mains by the transformers. Just FYI, shorting the output of the drivers won't damage them as by their nature, they limit the current to 350mA/700mA. Reverse polarity can damage them though...

If you bought these ones: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...A:IT&ih=015 , they are most definitely not made by Philips, despite it saying "Luxeon LED Lamp" in the title - they're cheap Hong Kong types. A quick way to check is that the emitter is made has a black round plastic base...

Indeed. I'm very suspect of some of these ebay LEDs though, I may purchase one to test at work to see how the spec sheets compare to real performance. I've noticed in the past that they tend to run a lot hotter than similar Philips LEDs running at the same power which is an early indication of...

Not sure where you've come to this conclusion from. Comparing lumens to lumens, halides are still more efficient than consumer available LEDs. A standard 150W metal halide has a light output of 12000 lumens. One of those 3W LEDs has a light output of 80 lumens, so you'd need 150 3W LEDs to...

They're wired in series with a CC driver, so 700mA in total. No problem there. Treating each LED as an individual would be a poor way of doing this. You'd need a driver for every LED! Highest efficiency (cost and power) is obtained from switching CC drivers and chains of LEDs in series. That...

I disagree. You would need at least THREE faults for mains to appear on the secondary. Remember the coils are never wound directly onto the laminations - there is a plastic former which the coils are wound around, which can either be two completely separate mouldings to maintain isolation or a...

The power supply he has used has a proper EI core transformer in it. An RCD would do nothing for protection as the secondary is fully isolated from the primary. Get some current limiting on those LEDs swiftly though - they will not last long as you have them. Those transformers are notorious...