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Last update: Mon Oct 15 22:56:20 2018Basic aquarium lights based on 555, MOSFET and leds.
PrincipleI was a shameless sinner who made aquarium lights with a resistor to limit the current and a boost converter. I have no excuse. And when the powers of the aquarium decided that water spash would finish eating the copper of my connector, I understood the message from above (well, below in that case since the water is below the leds): make it right.
So I'll use a proper power source, with led strip (still) and PWM modulation (which means 555). Basic circuit, but the best answer to a basic need.
Points of interrest555 and PWM made simple: honnestly I didn't find aywhere on the net any simpler PWM with 555 circuit. 2 resistor, 1 cap, 1 diode and you get a range from 1% to 99% duty PWM, this is the simplest 555 PWM circuit I could find. Just what you need in most cases. Other circuits have more parts without being that much more complex to be honnest. Let's use this one and see.
The idea is to set the simplest possible astable 555 oscillator. One other very similar circuit is here, with an online calculator.
In a nutshell, the key ideas are (from above site):
Bill of materials
SettingsWith a measured duty cycle of 50%, we're at about 5-7kHz (forgot exactly), and with a bit less than 2 meters of white led strips we have a comsumption of 0.47A at 12V (says my power supply). It's bright enough, and after a couple hours of continuous running, the "hottest" component was the 555 that went lukewarm. All the rest and especially the MOSFET staid at room temperature.
That's what I made↑
Source codeNone in this case, there's no mCU.
The circuit on the simple PCB in shape of breadboards. Love these for simple circuits.
Nota Bene: if you follow this link you'll find a simpler version with only 2 resistor and 1 cap BUT the minimum duty cycle I can get without the Schotky diode is 30%-ish (100 ohm/100ohm/0.1uF). With a simple Schotky diode, you get a 1%-90% duty easily.
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