How do I choose G4 LED, G5.3 LED, GY6.35 LED?
Product instructions of G4 LED bulb, G5.3 LED bulb, GY6.35 LED and G8 LED G9 LED. How do G4 LED, G5 LED bulb, GY6.35 LED, G9 LED compatible with transformer and dimmable LED driver?

1. What is a Bi-pin of G4, 5.3, G6.35, and GY6.35 base? You can identify most Bi-pins bases by looking at the pin spacing and how they look. Two pins come out of the bulb's bottom. These pins can be installed by gently pressing them into the socket. G4, G5.3, G6.35, GY6.35, G9 mean different type of lamp pins. G or GX is the plug-in lamp. The numbers after G indicate the distance between the pins' center points. 4 refers to the distance between pins of 4mm, 5.3 refers to 5.3mm, and 9 refers to 9mm.

What is different between  different Bi-pins:

Difference Between Gy6.35 & G6.35 Base: Are g6.35 and gy6.35 interchangeable? Yes. Under the IEC code system, G6.35 represents a bi-pin base with a 6.35mm pin spread and 1.0mm-diameter pins. A GY6.35 base code represents a bi-pin base with a 6.35mm pin spread and a 1.25mm-diameter pin.  Both G6.35 and GY6.35 are base codes for lamps with bi-pin base connectors, sometimes called miniature Bi-pins or mini-Bi pins. Under the code system set by the International Electrotechnical Commission a G6.35 lamp base has 1.0mm-diameter pins, while a GY6.35 lamp base has 1.25mm-diameter pins. But there are spring plates inside the lamp holder, So g6.35 and gy6.35 are interchangeable.

Difference between GU10 and GZ10:GU10 base, The numbers in the name, stand for the distance between the pins. So, with a GU10, there's a distance of 10mm between them. Please keep in mind that there’s a difference between GU10 and GZ10! A GZ10 lamp only fits in a GZ10 fitting, while a GU10, with its rounder base, fits in both. The “U” is an abbreviation for “Universal”.

Difference between GZ5.3 and GU5.3, G5.3 vs GU5.3 GZ5.3: GU5.3 LED  bulb, GU5.3 base, The 5.3 indicates the distance between the pins in millimeters 5.3 millimeters. Just the same as with the GU10, there’s also a GZ5.3 version of the GU5.3. The difference is just the same, a rounded (GU) or a rectangular base (GZ). So, a GZ5.3 won't fit in a GU5.3 fitting, but it will work vice versa. GX5.3 GU5.3 GZ5.3 use in MR16 led bulb spotlight cup, G5.3 LED bulb can be a spotlight or with G6.3 Bi pins led bulb similar G4 LED bulb, But G4 pins have a diameter of 0.8 millimeter, G5.3 pins have a diameter of 1 millimeter.

G4 vs GU4: Please be aware that G4 and GU4 can often be confused; although they're distinct. While both share a 4-mm pin spacing, the diameter of pins in a GU4 bulb ranges from 0.95-1.05mm when compared to G4 bulbs which measure from 0.65 to 0.8 mm. GZ4 GU4 indicates the distance between pins as 4 millimeters - suitable for use with the MR11 led bulb spotlight cup.

2. Measure the space between the pins in millimeters. List below measurement will help you find the right base type.
Base      Pin Spacing
G4 GZ4 GU4 are 4 millimeters
G5.3      5 millimeters
G6.35    6 millimeters
GY6.35    6 millimeters
G8    8 millimeters
GY8    8 millimeters
G9    9 millimeters
Diameter of pins: G4 pins have a diameter from 0.65 to 0.8 millimeter, GU4 bulb ranges from 0.95-1.05mm, G5.3 pins have a diameter of 1 millimeter, G6. 35 pins have a diameter of 1 millimeter, GY6. 35 pins are 1.25 millimeters in diameter.  Note that,  Some Bi-pins for example G4 pins may be rounded, square, grooved, fat or slender.

Above images show you the DIFFERENT Bi-pins G4 vs G5.3 vs G6.35 vs G8

3. What is the difference between constant voltage G4 LED and constant current G4 LED
Constant voltage and constant current mean two kinds of drive solutions.
The input voltage for constant voltage G4 is DC12V.
The input voltage for constant current G4 is AC12V, but DC12V can be used for constant current G4, so the constant current G4 is also called AC/DC universal G4.
3. Power for low voltage G4 and G5.3
The drive voltage is 12V for low voltage G4 and G5.3, there are some common 12V power: switching power supply(DC 12V), electronic transformer(AC 12V), LED driver (3*1W,DC 12V). The following table is about compatibility of 12V power:

                12V power

Switching Power (DC 12V)

Electronic Transformer(AC 12V)

LED Driver(3*1W)



Low voltage G4

Constant voltage G4



Dark light or off

Very bright→dead lamp

Constant current G4





Low voltage G5.3





4. Low voltage G4 LED, G5.3 LED, GY6.35 LED and switching power
Switch power is DC output, usually used for household appliances, such as table lamp, electronic balance, massage device, LED lamps ,safety and security monitor, digital products, computers etc. The output parameter include output voltage and output current, when output voltage is fixed, the switch power is differentiated by output current. 12V switch power have kinds of output current: 500mA, 1A, 2A, 5A, 15A, 30A etc.
When multi lamps are used, it has to use parallel way to access to the circuit so that the link can work normally.
The numbers of lamps that a switch power can carry can be calculated by following way:
Lamp numbers= ( switch’s power/ actual power of lamp) *0.8
5. Low voltage G4 LED, G5.3 LED, GY6.35 LED, G9 LED and electronic transformer
The electronic transformer is AC output, usually used for crystal Light, industrial equipment etc. The output parameter includes output voltage and power. The electronic transformer is differentiated by power, like 20W, 40W, 50W, 80W, 120W, 160W, 200W transformer etc.
Although it is AC12V output, 20W transformer can be compatibly used with constant voltage G4 due to low load value.
But more than 20W electronic transformer, it can’t be with constant voltage G4.
Our constant current G4 and G5.3 can work compatibly well with electronic transformers of 20~160W, for more than 160W, part of them can be compatible.
When multi lamps are used, it has to use parallel way to access to the circuit so that the link can work normally.
Generally, 20W transformer can drive lamps from 1 to 10pcs, the 160W can take 1~30pcs lamps. If the numbers of lamp are more than the maximum, it may destroy the transformer
6. Low voltage G4 LED, G5.3 LED, GY6.35 LED, G9 LED and LED power
LED drive is constant current output, the output voltage is not fixed. 3*1W LED drive is the most common, with almost 12V output voltage, often used for low voltage G4 as 12V power.
LED drive can’t be used for constant voltage G4, or it will be over bright and big droop, even the lamp is dead. The constant current G4 and low voltage G5.3 can be driver by LED power because there is constant power board protecting it inside.
One 3*1W LED only can take one constant current G4 or one low voltage G5.3.
7. The input voltage of high voltage G4 led, G8 LED, G9 LED
High voltage G4 LED G8 LED G9 LED is work  on maains voltage input, It is usually AC 220V or AC 110V, or can be customized.
High voltage G4 and G9 don't support changeable light function and can't be connected with the dimmer. Or it will cause dead lamp.
8. High voltage G5.3 LED input voltage
High voltage G5.3 LED is with wide voltage input, from AC 85V to 240V, but don’t support changeable light function..
9. Precautions for high voltage products
① Please use proper voltage input according to local power request;
② Please pull out the products when power is off;
③ Please don’t touch the lamp when it is used;
④ All products are used indoor, avoiding to be stored and used on the wet and moist surroundings;
⑤ Please don’t pull out the products too often
⑥ The heat of lamp is normal.
10. How do G4 LED, G5.3 LED, GY6.35 LED, G9 LED compatible with electronic transformer?
A. Constant voltage G4, Mean use DC 12V Input voltage, and it can let the driver to be swtich power(Input voltage DC 12V), Or 20W Electronic transformer(Input is AC 12V, Over 20W, example 40W,60W Electronic transformer won't work)
This kind of GU4 can't use LED Driver, nor use over 20W Electronic transformer as it used for 1 pc G4 connector(20W Electronic transformer. Or if you use in engineering project(use a lot of G4, to save cost, one pcs switch power can drive
many constant voltage G4).
B.  Constant current G4: Which means input voltage can be AC 12V Or DC 12V, We call AC/DC GU4, to be able to let it work include:
① Power supply(Output is DC 12V),
②Electronic transformer(Output AC 12V, 20W~160W,currently most of constant current G4 can be compatible with the electronic transformer less than 160W). Over 160W ,Some can be compatible,
some are not but of course this type of electronic transformer is rare.
③ LED Driver (3*1W,4*1W) This type of G4 can use LED Driver, price is a little higher.
C 3V G4: It means input voltage is between 3~3.4V,to be able to let it work is only LED Driver(1*1W or For 1~3W)
This kind of GU4 only use LED Driver, can't use electronic transformer or switch power. This G4 is on the market as of the LEDs being used widely in the market. It only use the G4 pin but it is new to the market,it only come with whole LED Fixture.
The most common G4 are still being used to replace traditional GU4 Lamp so this type is not so popular.

Note: When you use G4, please try to use certain wattage of electronic transformers only example:40W or 60W but no 40W~50W. This is will hurt the LED
When you use G4, and if you are using OSRAM electronic Transformer, it won't work with LED G4s as of its inner electronic protection for its own halogen G4.

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