Raspberry Pi Forums

Brandon92

Okay, this video might give you some background of the MOSFET:

https://youtu.be/o4_NeqlJgOs

Edit
Turning on and off a mosfet is easier than PWM a mosfet.

Brandon92

Basically there is "no" lower limit of the drain-source voltage. The mosfet can switch between the 0V and the maximum drain-source voltage. You need a MOSFET driver to turn and of a MOSFET, like in my diagram. Do you want to turn on and off the heater element. Or do you want also to use a PWM signal...

Brandon92

Hello, The maxim drain-source voltage is one of the imported specifications of a mosfet. If you go over the maximum value that the manufacture specified. The mofset will break down. And you can not disable the heater any more. So, you should stay away from that value. Or in other words, the Vds need...

Brandon92

Hello,

Someone has, I believe, the same question in this topic. And I gived him some schematics to play with:
viewtopic.php?f=37&t=220214

Brandon92

Okay, that is indeed a little bit strange. I assume that the Peltier element is not connected to a heat sink? So, you can feel it directly if it heats up. So, I think you might have something wrong with your element. Can you see something physical wrong with that element. Otherwise, I think it is ti...

Brandon92

Okay, that a good sign that you are able to control the output voltage with your Rpi. This means that this part is working know. So, we are going the take a look at your peltier element. Would you like to disconnect everything from your power supply and measure his output voltage. And than connect t...

Brandon92

I also agree with drgeoff. That the onboard powersupply power the relay. And I (hope) that the optocoupler* is driven by the Rpi and that the optocoupler drive the transistor and then the relay. But as a isolation layer the optocouple his mean "feacture" is somewhat canceled by the traces under the ...

Brandon92

Ehm, okay. Did you also try the code in the "this one" link in my last post? In that code they also set the duty cycle. And the other driver is indeed not enough power to drive your Peltier element. You can test it to connect it to your power supply. I assume that this element is on a heat sink. By ...

Brandon92

Okay, did you connect the ground of your Rpi, to the ground of the driver. Like figure 4.1 (without the 5V connection and the resisitor and capacitor) I believe that the 32kHz is the switching frequency of the h-bridge and it done by the microcontroller on that board. So, you don't need a PWM freque...

Brandon92

You need to give not information than that:

what for sensor, so the type?
what for code did you try or made?
how did you connect it?

Otherwise we can not help you with your question. There exist a lot of sensors.

Brandon92

This statement is not true: "2-channel AC100-250V 30A Solid State Relay Module Board High/Low Level Trigger" Because it is a normal relay, datasheet . And the coil voltage is 5v. What for kind of load to you want to switch wiyt this relais. Depending on the load, the maximal switching current decrea...

Brandon92

First of all, how did you connect it exactly and how did you config the dip switch. And is the 50hz accepted for your driver and it does not need "something" else. And is there a special reason why you use the R/C function. Also, don't forget that the output voltage of your Rpi is 3,3v. And the inpu...

Brandon92

Hello,

Your link to your code is not correct. So, I can not see it

Brandon92

Hello, I have taken a quick look at the driver that you have chosen. But, you could also use it to drive you peltier element. I need to say it is a very expensive one. In comparante with this ones . I also found this movie about the controller. And this one could work without the Rpi. But I don't kn...

Brandon92

You could indeed drive a Peltier element by a single (modern) mosfet. The mosfets nowadays are strong (not recommended for your application by the way). So, 10A is not a really big problem here. Its just picking the right one for your task. But, before I recommend you one Do you have a experience wi...

Brandon92

Are you looking for this:

https://www.raspberrypi.org/magpi/android-raspberry-pi/

Brandon92

This is not quite right. The Pi3B+ normally consumes current -- let's say 1A -- from a 5V source. That equates to a resistance of 200R. Not a high resistance, though it might vary depending on what voltage the meter applies. With reverse polarity, the protection diode should give a low value (proba...

Brandon92

Iit doesn't matter where i place the positive or the negative lead. Sorry, but you are wrong here. As you might know, the multimeter will output a cirtain voltage/current. And if you place the positive terminal on the positive side of the Rpi power rail. The tvs diode does nothing And you will meas...

Brandon92

How did you measured it? Where did you place the positive terminal of your multimeter? And what do you measure in the resistance range (and place the positive terminal to the positive side on the Rpi.) And remember that there is a tvs diode on the input as protection. So, you will measure a diode in...

Brandon92

What is the type of relais that you are using?

Brandon92

I would advise to use a well know power supply manufacture (meanwell, traco power, and some others). This is because they have build in safety features. And they made the cleamed specifications. Some features are over current protection and over voltage protection. So, you know if there is something...

Brandon92

I don't think it is a good thing to drive a mosfet without a gate resistor. Because this could damage the gate internal. For example if you apply a pulse (20v) with a high dv/dt, the current through the gate capacitor (Ciss) can be to high. And can kill the mosfet. In this case there could also be a...

Brandon92

We talked to some people they suggested the Pi might crash if it is operating that many motors. You can connect as much motors as you want*. And if you connect them in a correct way (and also the power) your Rpi will not crash. So, you need take a appropriate circuit to control the motors and also ...

Brandon92

First about you electric shaver: I think you got scammed with this one, you have the S3110 and NOT the S3580. Because when I look at the official webpage . It is stated as a dry electric shaver only. And you can only use water to clean you shaving head. This is also stated in this offical link (Imp...

Brandon92

I have also a electric shaver from Philips that I can use in the shower. However when I charge that device, I can not use it. (It will not turn on when connected to the charger).

So, Is there something written in the manual about this. And also your picture is different than the provided link.

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