Can I use this mosfet?
A03400a

Yes...but the gate would be operating at maximum voltage (+/-12v).
It would be better if you chose one with a higher maximum gate voltage.
A least +/-15 to +/-20v would be better (the CD4000 series can operate up to 18v).

 

Can I use this mosfet?
A03400a

No it can only handle 1.5 watts max.
That mosfet is designed for PWM or as a Load switch not for high current linear applications.

 

No it can only handle 1.5 watts max.
That mosfet is designed for PWM or as a Load switch not for high current linear applications.

Where does the datasheet indicate that?

 

Where does the datasheet indicate that?

 

View attachment 337132

That's without a heat sink but even without a heat sink at 2A it will barely get warm.

 

Yes...but the gate would be operating at maximum voltage (+/-12v).
It would be better if you chose one with a higher maximum gate voltage.
A least +/-15 to +/-20v would be better (the CD4000 series can operate up to 18v).

Like what part number mosfet smd?

 

That's without a heat sink but even without a heat sink at 2A it will barely get warm.

The TS wants to use that A3400 mosfet for M1 in this circuit:
M1 is in linear mode. I believe there are three LED strips each for M2 and M3.
That's a total of 12 amps which is twice the A3400 rating.
Assuming half load is 6 amps at 6 volts that equals 36 watts of dissipation.

 

Like what part number mosfet smd?

Need to use the PWM circuit in post #10.
No way to use that circuit in post #3 within that 13X100mm space.

 

I believe there are three LED strips each for M2 and M3.
That's a total of 12 amps which is twice the A3400 rating.
Assuming half load is 6 amps at 6 volts that equals 36 watts of dissipation.

3 led strips?, they are only two
From where the 12A came from?

 

Need to use the PWM circuit in post #10.
No way to use that circuit in post #3 within that 13X100mm space.

I can use A3400 here?

 

I can use A3400 here?

Yes

 

Only one led s

three LED strips each for M2 and M3.
That's a total of 12 amps which is twice the A3400 rating.

Only one led strip for M2 and one for M3

Try this version.
M1 requires heat sink!
View attachment 337043

EDIT: Changed mosfets to IRZF44N, lower Rds.

This capacitor exist in smd package?

 

This capacitor exist in smd package?

It does but actually don't need a 400 volt rating. Look at this capacitor.
Another less costly option if mounted flat on either side of the pcb. This

 

It does but actually don't need a 400 volt rating. Look at this capacitor.
Another less costly option if mounted flat on either side of the pcb. This

Ok, I've looked, thanks
Now I have one more question
Is it possible for this circuit to turn on one lamp, when on/off button pressed?
As I've noticed that it's not, and I have to press brightness button to start light
How can I achieve this?

 

Q1 will hold the brightness from the last setting.
It might be only on the very first time the unit is power up that the high button needs to be pressed.
Let me look into this.

 

As I've noticed that it's not, and I have to press brightness button to start light

On the breadboard the LED always comes on at a low brightness level.

 

If i use A3400 instead irf520, the circuit will function same or will be any different?

 

Should be the same but use only one LED strip per A3400 mosfet.

 

Should be the same but use only one LED strip per A3400 mosfet.

Ok