Having previously bought one of these lamps as just the housing and LED, I bought the full thing on ebay to see how the power supply was implemented.
It's not really fantastic. The regulation is appalling with the power of the light being around 1W at 12V but actually peaking at around 2W at 7V.
The chip being used inside is an MC34063 switching regulator that can be configured for boost or buck operation. Strange that with such a capable chip the actual regulation is so poor. I guess they just used it in the simplest and sloppiest configuration possible.
It's not really fantastic. The regulation is appalling with the power of the light being around 1W at 12V but actually peaking at around 2W at 7V.
The chip being used inside is an MC34063 switching regulator that can be configured for boost or buck operation. Strange that with such a capable chip the actual regulation is so poor. I guess they just used it in the simplest and sloppiest configuration possible.
This may well be the first YouTube video I've seen that doesn't have a single thumbsdown.
The input power curve is completely rational for a constant-power lamp (constant-current through the LED). At low input voltage, the input bridge burns more power due to higher input current across a constant voltage drop across the bridge. The lamp is less efficient a low input voltage, so the input power needs to be greater at low input voltages to maintain a constant output power.
The MC34063 is actually a weird chip. Due to it's I peak oscillator you can't properly design the circuit due to tolerances in such low ohm values and solderin processes. The idea may be great but I designed NE555 LED drivers that were way more efficient. I never liked this chip anyway. It needs 0.1 to 0.2 ohms for its Ipk oscillator which is just retarded.
I wonder if it's to try giving improving the power factor when used on an AC supply such as when used with a step down transformer. Another possibility is to give the impression of reduced flicker by boosting the light output just before and after the AC cycle passes between 4V to -4V.
Does the light just have the wrong rated LED for the circuit board its wired to ?
I have a lot of 12v ac led lights here and they all have that hard glue but I cannot shift it as it is a bit flexable.
Also these lights run on 12v ac tend to wipe out TV as well as FM reception over a about several 100 sqm from each light.
..eddie