Intro: Radio Voltage Steal
How to hack your radio so supply 9 or 12 DC Voltage.
Step 1: What and Why
Hacking the radio supply would able you to have an excellent stabilized generator, for 11-12 volts, or 6 volts, if you continue to use the clock in the same time.
In the radio, the voltage supply, is composed by :
This system is called "Output Smoothing" : principle : http://en.wikipedia.org/wiki/Image:Diode_bridge_smoothing.svg
The transformer supply 9 or 12 volts in AC, and the diode bridge transform it into DC, but there is always "variations" of current, then there is a capacitator to avoid this problem and have a stable DC.
A generator like this cost, approximately 20 â¬ -16 $ in an electronic store.
Step 2: Tools
The tools need :
-A brain (very cheap)
-An Iron Solder
-Multimeter : The most important thing
-Solder wire (I used Sn:99.3 and Cu:0.7%)
Step 3: Disassemble the Radio
Where, now we'll disassemble the radio to find what is interesting, but we wont destroy the radio though, just steal the current .
Found the screws, and remove them, in order to open the radio. Here in my radio there's only 4 screws.
Then, open it and look for the transformer and the first 4 Cables. There is 2 output for 1 input.
Red - Yellow, and Blue-Yellow . But they aren't interesting right now. What is interesting right now is the diode brigde : next step
Step 4: The Diode Bridge
The second important part in a generator is the "AC-DC" commutator. In other words, the little thing which transform AC into DC.
The diode bridge principle is simple, just type "Diode Bridge" in Wikipedia or in Google. It's real simple system.
But so, no theory just practice here :
The diode bridge is always present under this form :
4 Diodes (tiny black/grey) and capacitator (big blue piece). Try to find it and look for the contacts on the other side. I mean the capacitator have 2 poles + and - , which are in the bottom of the board.
If you get the voltage at diodes poles, the multimeter will show 3 v or 6 v ... because it changes ... at 50 hz !
In some radios or machines maybe you'll find another very little part between diodes, which are "inductors". But, in a simple radio-clock-alarm it doesn't matter.
Step 5: Get the DC Current !
Well here, just put up the main board of the radio and find the poles of the Capacitator. Here with my radio, i've 11.40 volts.
An important law of electronics says that if you get the current you wont have 11.40 v but 11.40/2, if you still use the radio/clock in the same time.
Now we'll find the poles, and connect to them :
Mines are indicted by my finger .
Step 6: Mesures
Well here, the final step : get the voltage values with the multimeter, to find the right place to connect your wires with the solder. but DONT solder the capacitator poles, be gentle just don't sold the capacitator :
Follow the circuit until another 2 poles of dc current and sold the wires there
I'ven't photos yet because i'ven't 4 hands " and the 3rd hand isn't photographer " . But simply put a little bit of solder wire on the existing pole and put the wire on, just like a simple soldering method.
/!\ Not for kids, Solder Iron is dangerous /!\
And be careful to don't destroy the radio
In the multimeter is show - 11.34 just because i've put the wires in the bad polarity. Nothing interesting. The voltage in DC is 11.34 V !!!
Next get 2 longs wires and sold' them to the capacitator and put the wire out of the radio (from a free hole for example) and assemble the radio, as you disassemble it .
Just enjoy this radio/clock hack !