Which transistor to take for the key?

Question

PHP

I have been familiar with electronics for a very long time (you can say from childhood), but there is one of the topics that constantly raises questions for me (apparently due to not often colliding with it) - field-effect transistors.
Here and now. I want to test one seven-segment indicator (FYS-30011AUA-11). Each segment asks for about 18V voltage from him, and to connect it to the arduino, you need a “converter”. At first I thought about using an optocoupler, but I decided that it was somehow difficult, I decided to use transistors, but the question arose, bipolar or field ones. Everything is clear about the bipolar ones, but there are questions about the field ones:

1. after all, who is better for these purposes, a field worker or a bipolar
   
2. how to choose the right field
   
3. what kind of strapping should it have (in particular, is it necessary to put a resistor on the gate between it and the arduino)
   

Answer 1

To test for NULL, the following expression should be used: IS NOT NULL , not !=null

Answer 2

And, for now, the first question remains open

The answer to it is elementary - a field worker is better, since its application is simpler. Only one resistor is needed in its strapping (and even that is not necessary), and a minimum of energy is required for control. If a bipolar specialist needs a significant base current, which often causes compound transistors to be blocked, then a field worker does not have this current at all - he only needs an opening voltage of half a volt-volt above the threshold. And that's it. The only difficulty is to prevent accidental breakdown of the shutter by static during installation.

voltage in the region of 15-18V, current not more than 30mA

The second advantage of the field worker is versatility. No need to puzzle over its type - any is fine, just choose the right channel type, P or N. And don't be distracted by big numbers, 40 volts and 100 amps - it will perfectly switch your 30 mA at 18 volts.
The third advantage of the fielder is better key properties. Try to get a few milliohms from the public key on the bipolar - it will not work. And on the field - it's easy.

Answer 3

In all incomprehensible moments, I advise you to use IRLB3034PBF.
With opening 3v, it is able to pass more than 100 amperes. Operates up to 40V load.
Connecting and piping all mosfets is very simple.
Please note that you are in control of the minus. (by earth)

Answer 4

1. after all, who is better for these purposes, a field worker or a bipolar

It doesn't matter, they work in key mode
Normally. The collector-emitter voltage (drain-source) and the collector (drain) current are 1.5-2 times higher than the load current voltage.
For the field worker, no strapping is needed, the gate current is microscopic, but in the event of a breakdown of the transistor, it is worth putting a current-limiting resistor based on the maximum current <35mA (>500Ohm)

Answer 5

Use the IRL series field switches, they are designed to control the logic signal.