## Introduction: Replacement of the Radio Bulb With an LED Diode

We will create an eternal light bulb for our transistor radio.

## Supplies

White LED diode 10mm, original non-functional bulb with E10 thread, resistor, modeller drill, solder, tin.

## Step 1: Preparation of the Bulb Body

Carefully take the bulb into the pliers and crush the glass.

## Step 2: Removal of Internal Impurities in the Sleeve

Using pliers, gently press the edge of the sleeve around until the internal dirt such as glass and glue break down.

## Step 3: Drilling Holes for Components

Remove tin solder on the bottom of the sleeve. Then we drill 1mm holes on the bottom and side according to the photo, here we will thread the component leads.

## Step 4: Soldering Series Resistor.

A series resistor is required to protect the diode from incorrect voltage. Its value depends on the supply voltage of the original bulb and the current of the selected diode. For example, my diode is white with 3.6V parameters and a current of 20mA and the supply voltage is 9V. There are many online calculators on the Internet for calculating resistance, but it is a simple calculation. Subtract the working voltage of the LED from the input voltage and divide the result by the diode current in amperes.

R=Uz-Uf/I ( Uz - input voltage, Uf - LED diode operating voltage, I - LED diode working current )

R=9-3.6/0.02( R= 9V - 3,6V / 0.02A) = 270 (Ω)

The resulting resistor resistance is therefore 270 ohms. We connect the resistor to one diode terminal.

## Step 5: Soldering Components to the Body

Thread the component leads through the case and solder. At the end, we just adjust the position diode on the socket. You can apply a little glue under the LED housing to the socket for reinforcement.

## Step 6: Finished Product

We can attach the finished bulb to the radio. Remember the polarity of the voltage, in some cases you will have to swap the supply wires under the bulb holder. I have found that the bulbs of some desktop radios are powered by AC voltage directly from the transformer. This voltage is not suitable for the LED diode, therefore it is necessary to include a rectifier with a smoothing capacitor between the LED diode and the transformer. We measure the resulting voltage and calculate the series resistance according to the result.

CAUTION, WORK ONLY WITH LOW VOLTAGE, IDEALLY TO 12V. I AM ARE NOT RESPONSIBLE FOR ANY INJURY CAUSED BY IMPROPER PROCEDURE.

P.S. Excuse my bad English :)