UK Charger 5V 2A JHD-AP012B-05200AB


Official specifications: I got it from Ebay

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The charger can deliver about 2.9A before overload protection kicks in.


This drops to about 2.8A at 120VAC


The charger can deliver 2A for one hour.
The temperature photos below are taken between 30 minutes and 60 minutes into the one hour test.


M1: 50.3C, HS1: 56.0C


M1: 63.9C, HS1: 69.9C
HS1 is the rectifier diode.


HS1: 61.1C
Again HS1 is the rectifier diode.


M1: 52.3C, HS1: 56.5C


HS1: 74.8C
HS1 is the transformer.


At 0.5A the noise is 5mV rms and 106mVpp.


At 1A the noise is 7mV rms and 145mVpp.


At 2.5A the noise is 7mV rms and 97mVpp, this is very low noise.

Tear down


It was a bit hard to break apart, but some screwdrivers uses as prybars worked.


A very compact design, it must be expensive to mount all the parts.
At the mains input is a fuse in shrink wrap and a MOV to handle mains transients. The bridge rectifier is four diodes (D1..D4). There is two smoothing capacitors (C1 & C2) with a inductor between. The mains switcher transistor (Q1) is next to the safety capacitor (CY1).
On the low volt side is a large rectifier diode (D7) and two smoothing capacitors (C5 & C?) with a inductor between.
There is a opto feedback.

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The bottom of the circuit board do also have a lot of parts, mostly passive, but there is the switcher IC (U1) and on the low volt side the reference (U3: 431). There is space for a auto coding chip (U4), but it is not mounted.


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Across a slot there must be 4 mm between mains a low volt side, there is a lot more space here. Directly across circuit board there must be above 6mm, but here it is slightly below 6mm!

Testing with 2830 volt and 4242 volt between mains and low volt side, did not show any safety problems.


The charger is a bit old fashioned in the design, but it works nicely with enough current and low noise. Safety is not perfect, but the problem is minimal.


The USB charger was supplied by a reader for review.

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