Using MOSFET transistors instead of SSR relays with nodeMCU v2

I am currently using the circuit shown below to multiplex the input to two 7-segment LED displays from a single output of the ESP8266 chip. This is because I have ESPeasy software installed on it. Such software can only work with one such display, so I have to 'trick' ESPeasy into thinking it only works with one display, while it de facto works with two. All switching is done using the 'rules' defined in the ESPeasy configuration. The relays I use are small solid-state relays of the SSR type (this is so that there is no 'flopping' effect). But this solution is too expensive and too large compared to using MOSFETs, for example, such as the 2N7000.

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Unfortunately I don't have enough knowledge hence I am asking Fellows on the forum. How can I replace the relays shown in the picture (along with the bipolar transistors controlling them) with MOSFETs ?

mackowiakp wrote:

How can I replace the relays shown in the picture (along with the bipolar transistors that control them) by MOSFETs ?

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This route, in any case, is not optimal, because you are dealing here with logic signals and the switching can be taken care of with a ready-made multiplexer. For example using 74HCT4052, 74HCT4053 or similar. You can control it with one bit if you don't have a "none selected" situation.

A bit contrived. Wouldn't it be better if you connect the DIO and CLK from the individual displays to different pins on the ESP8266? You will also use up 4 pins.

Added after 17 [minutes]: .

mackowiakp wrote:

This is because I have ESPeasy software installed on it. Such software can only work with one such display

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But I guess you can define two different actuators?

CLKs are connected together anyway. Only the DIOs are switched. In the ESPeasy software you cannot use two such displays (answer from the developers). Hence the switching. As to whether there is a "none selected" situation, the opposite occurs. Both selected. This is at boot time when both chips are receiving initialisation instructions.

mackowiakp wrote:

As to whether there is a "none selected" situation, the reverse occurs. Both selected. This is at boot time when both chips receive initialisation instructions.

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Well, in that case, a multiplexer is unlikely.
But you could successfully use a chip with 74HCT4066 keys or similar and stay with your original concept. Much smaller and better than folding mosfets or relays.

I think I have found a solution. Let's look at a single channel of a 3.3V to 5V converter.

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If we control the gate of the transistor directly from the GPIO of the ESP8266 then we have a multiplexer and a converter in one. And I have to use the converter anyway even though the TM1637 works fine when powered and controlled from 3.3V. And this is because I am using blue displays which light up poorly with a 3.3V supply. I will buy the transistors on Monday and give it a try.

Everything you write is right. That's why I wanted to use displays based on the MAX7219, which is also supported by ESPeasy. These ICs have a "chip select" which would take care of the multiplexing problem. Only they didn't have any in the shop in the blue colour I wanted.

Baywellian. I found an even simpler solution based on a bipolar transistor, and I have one in my drawer:

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The converter is admittedly unidirectional but that's all I need. I connect the base to the GPIO and it should work.