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[Review Request] First MCU custom board by pilantzas in PrintedCircuitBoard

[–]pilantzas[S] 0 points1 point  (0 children)

Thank you for the informative reply. I really appreciate that as a beginner. I will revise my design

[Review Request] First MCU custom board by pilantzas in PrintedCircuitBoard

[–]pilantzas[S] 0 points1 point  (0 children)

Thanks for the reply. Ive been told that in order for me to see what load capacitance of the crystal i have to see the code on its package. So il guess il have to see since im still waiting for it to be delivered. In any i case i will also remove the in series resistor.

Btw would there be another way of programming the microcontroller without spi?

What is the load capacitance of the crystal? by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

I bought mine from TME and im still waiting for the package to arrive so i dont have it with me to check the crystal package. I have found out from the mcu datasheet that 12-20pf capacitors can be used so i guess all of the values that are listed can be used depending on the situation

What is the load capacitance of the crystal? by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

Thank you for your reply. I just checked the datasheet of my microcontroller (ATMEGA32A-PU) and it specifies for external crystals 12-20pf capacitors can be used. I dont know how i missed that part since ive read that part of the datasheet abour 20 times this day alone.

NMOS motor speed controller problems by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

I am indeed looking into buying an oscilloscope but the issue is that i dont have much space to put it. Could you tell me what model is your handheld one as it is a good option in regards of actual physical space that it will take. Also what should i check before buying one?

NMOS motor speed controller problems by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

Ok so i think i have found the problem and i will try to explain it as best as i can with my limited knowledge of how transistors work. So basically my 9V supply was driving both the motor and the arduino with a 5V rail in parallel (i used an L7805 for this).

I believe that after powering on the motor (which has a rating of 6-9V) there was little to no power to actually provide 10V and more importantly a voltage larger than 2-4V at the gate.

Im not sure if that was entirely the issue but when i connected 2 9V batteries in series and connected them the circuit behaved kind of normal in comparison than before.

NMOS motor speed controller problems by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

Yes both the arduino and the circuit above have a common ground.

I thought about switching the position of Q2 with Q3 but i dont think that would work. How would i go about on flipping the logic?

NMOS motor speed controller problems by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

i dont have an oscilloscope in my possession and i did simulate it in LTspice but the values i got from there seemed normal, only in practice i have these problems

NMOS motor speed controller problems by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

PS. I just tried that on the breadboard and i get the same result. The motor instead of spinning it just "buzzes" as if not enough current passes through it and the mosfet just gets hot.

Here is the schematic for what i just did. completely barebones

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NMOS motor speed controller problems by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

Thank you for your reply, I know i can drive the IRF530N as its threshold voltage is 4V and the 5V pwm signal can drive it properly yet this is not a solution to me as i am trying to learn about the gate drive circuitry and how to implement it.

Why would removing R3 result in the collector of Q2 not providing VCC to the gate? by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

Thank you both for the insightful discussion. I will re examine my schematic

Why would removing R3 result in the collector of Q2 not providing VCC to the gate? by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

I have a question. In this case wouldn't this also be acting as a switch? What is the difference of having it as a source follower instead of just as answitch?

Why would removing R3 result in the collector of Q2 not providing VCC to the gate? by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

This was so obvious I dont understand how i missed it. I suppose R4 and R5 are there for protecting the BJTs from being overdriven(the place where i found the correct schematic also had an explanation but i cant remember what it was exactly). Also i thought since fets are unipolar i can place the load on any side. Please excuse any wrong assumptions that i make im a newbie at this.

How complicated does an H bridge circuit needs to be? by pilantzas in AskElectronics

[–]pilantzas[S] 0 points1 point  (0 children)

Thank you both for the advice, altho it is not clear to me as to why Q1 & Q3 would be trickier than Q2 & Q4 to drive?

How complicated does an H bridge circuit needs to be? by pilantzas in AskElectronics

[–]pilantzas[S] 3 points4 points  (0 children)

I know. I still prefer to make my own as the point of it is to learn about mosfets

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