1Epoxy body (DIP-4) · DB107: 1 A, 1000 V
2~ + ~ − marks
3Pins: ~ ~ input, + − output

Small black DIP-4 body with “+”, “−” and “~” markings on top
DB107: small DIP-4 body; high-current types have square metal or plastic bodies

Diodes

Bridge diode

In simple terms

What is this?

A bridge of four diodes in one body; whichever direction the current comes from, it always sends it the same way.

What is it for?

Converts alternating current into one-way current that devices can use.

Where do you see it?

Inside the power supply of adapters, chargers and audio devices.

How do you spot it?

A small square or flat black body with four pins; it has two AC marks, one plus and one minus printed on it.

Caution:

Do not mix up the plus and minus pins; the two AC pins can replace each other.

Technical definition

Four diodes connected as a bridge in one package. Whatever the direction of the input voltage, the positive output always comes out of the same pin. Because current passes through two diodes while conducting, about two diode drops of voltage are lost.

ExampleDB107

Current1 A

Reverse voltage1000 V

Schematic symbol Same in IEC and ANSI

IEC 60617: the drawing style used in Türkiye and Europe.

Pins 4

1AC input 1Marked “~” on the body~

2AC input 2Marked “~” on the body~

3Positive output (+)Rectified DC plus+

4Minus output (−)Rectified DC minus−

Features typical

Max. reverse voltage: 1000 V (DB107)
Average current: 1 A
Voltage loss: ≈2 × 1 V (two diodes)
Streak: DB101: 50 V … DB107: 1000 V
Ripple frequency: 2 times the input (50 Hz → 100 Hz)
Warning: Mains voltage is outside this app's scope
Example part: DB107 (1 A, 1000 V)

Common mistakes

Using it without a capacitorThe bridge output is pulsating DC. For smooth DC, add an electrolytic capacitor across the output.

Mixing up AC and DC pinsLegs marked “~” go to the input, “+” and “−” to the output. If you connect them wrongly you short the source.

Forgetting the voltage lossThe output peak is about 1.5–2 V lower than the input peak.

Test with a multimeter

Test whether this part is good with the multimeter on the measurement screen.

Take a measurement

Where it is used

DC supply from a low-voltage transformerReverse-proof DC inputCharger rectifier