[Hi guys, I have couple of question]

Hi guys, I have couple of question :
1.) by providing isolation to control IC by pulse xformer, then how the control IC is powered at the first time it powered? since the auxiliary windings doesn't have a voltage at that initial time
2.) do we need more winding to drive the high side mosfet? since we know that the voltage at the gate should be Vth+Main DC Voltage

Thank you

[A problem about using an arduino to controll motor]

I'm trying to use 28BYJ-48 stepper motor with ULN2003 driver Arduino, i.e. move an object in one direction for a short time and then reverse it and then do a repeat while the power in still on. I have made lots of stuff (electronic clocks mainly) but this the first time I have used an arduino controlled motor. I do have a question. Normally I solder my connections but with the UNO board that does not seem to be necessary. Is that correct?

[I am having huge difficulty with op amp circuit]

I am having huge difficulty with op amp circuit used in TA7642 radios, I cannot figure out how to attach the lm301 chip to have a gain of more than 200 (10 u cap between pin 1 and if I give it too much signal in 50 k ohm pot then the radio just makes a farting noise. My problem is that I need to figure out which lowpass or highpass filtrations between the speaker pin 5 and the 470 n capacitor and which resistors I need to reduce the hissing noises without any distortion or clipping when I try to make it louder

[Give me some suggestions about buying a amp]

I need to clarify something regarding buying a amp, normally I am playing classical guitar also singing with backing tracks, which kind of amp should I buy for my purpose? And is it should be at least 50 w? If you can explain this thing it's a great help for me to buy a good amp

[Interface MPL3115A2 with an Arduino micro-controller]

Hello, I want to hook up a MPL3115A2 pressure transducer sensor and interface it with an Arduino micro-controller. But I have a question. I could set up the display and I can see it is working. The problem is that I get some random numbers, regardless of connecting the sensor or disconnecting the Arduino analog input from it. What might be the problem? Even when nothing is connected to the A0 or any other analog pin, I see the same behaviour. 
I appreciate any reply and help.

[Do you have some recommendations about MOSFET?]

I hope you can help me out: I'm going to use 12V supply to power an Arduino. I need to switch several high power laser diodes (2 V, 3.5 A) on and off and I have to be able to modulate the power from the laser diodes. If I want to control the MOSFET with PWM, can I still use that driver and MOSFET to control de current in the diode? If not, what driver and MOSFET do you recommend? I assume I will use 12 V to power the driver and the MOSFET gate, but I need 2 V for the laser diodes.

[Charger firmware]

Hello, everyone.

I need the HEX file for the charger HTRC B6 V2, I'm looking at Google Uncle but it doesn't help, the charger can't read the file. Hex because it's protected, at least I can't read it I got a message "device is protected"

The charger is Procku STM8S207R8T6, I wrote to HT-RC but to no avail.

[Is it compatible to use this STM32 card with an SD card reader?]

I want to use this STM32 card with an SD card reader and a WS2812b LED strip. Is it compatible? Is there differences with Arduino's code ?

[L293DNE Quadruple Half-H Drivers]

I have read something about L293DNE, it is a good article,

and I WONDER if you have more ideas from yours.

[Fuse size for dual amps]

I currently have a 4 channel amp powering my speakers in my car. I am planning on getting a 12" sub and an amp to power it. I have a 4 gauge wire run all the way to the trunk for my current amp. I am going to get a distribution block and run the 4 gauge wire to the block and 8 gauge wire from the block to each amp. My question is how do I go about determining what size fuse to use. I already have a 60amp fuse for the current amp and I'm not sure what size fuse I will need to replace it with. The new amp will most likely need a 60amp fuse as well so do I run a 120 amp fuse or keep my 60 amp fuse. I'm pretty sure I just need to run a single 60 amp fuse but I want to make sure before I start buying stuff. Thanks.

[Can I replace ATTINY13A microcontroller by ATTINY13?]

I bought a ATTINY13A microcontroller after reading a detailed introduction article about this device, here's the link: ATTINY13A datasheet. It gives me their comparison about specifications. But I found that the main difference is that ATtiny13A generally consume less power at the same voltage and frequency.

Can these two be used interchangeably?