teleghost2014-02-14 10:28:53
Do it yourself
teleghost, 2014-02-14 10:28:53

Another remote RESET on an opto-relay?

Dear electronic monsters* ,
I've set myself up with some kind of junkyard competition (i.e. without Arduino) and am making another PC server remote control system, this time from a MOXA NE-4110S interface converter (converts Ethernet <-> RS232) for $50.
This device has a microcontroller and four TTL digital ports (input or output is set by software). Initially, I wanted to just connect it port-to-port with a null-modem cord to the PC motherboard (serial console), but, inspired by the post of the respected workDNK, I decided to complicate the task and add a remote reset (RESET) and even power on / off (without Wake-on-LAN). While the adapter ordered in the store is coming to me, I ask for help in solving this promelectronic puzzle, because with transistors, I'm on "you", despite the experience in IT.
So, the NE-4110S has digital ports, but according to the documentation (pp. 3-8) , their output current is limited to 1mA, and it is clearly not enough to open the KR293KP4B opto-relay (in my opinion, opto-relays do not open with such currents at all). After searching the Internet, I drew a circuit on transistor keys, its task is to open and close a two-channel opto-relay with a low current of digital (TTL) ports DIO3 and DIO4. The rest has already been checked by workDNK , respect to him and health.
cd741a9de10b479e8b88e352d179ca2d.png(link to diagram)
I chose the KT315Zh transistor based on the maximum current of 50mA (the KR293KP4B relay opens at 10mA) and the worst current transfer coefficient (since this is a key, not a radio receiver).
1) Will it work (i.e. open and close the opto-relay on a signal from digital ports)?
2) Are the transistors selected correctly?
3) What resistances should be put on the bases (R1, R3) and collectors (R3, R4) to achieve the desired currents?
4) Do I need to add something? Capacities there or something else?
5) Is protection against burnout of the digital port of the microcontroller guaranteed if it is configured for input instead of output by software?
If everything works out, I promise to buy a breadboard, assemble this ham radio kit and report back on the results. There is still a fight with the LEDs ahead (reading the state of the POWER LED).
* Monsters of electronics is a long-forgotten fidosh meme, born as a result of an attempt by one comrade to create a virtual reality helmet.
And here is my first electronic circuit on a solderless breadboard, it remains to wait a bit for the interface converter and it will be possible to stick it into the hardware:

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7 answer(s)
tugo, 2014-02-14

1. Will work.
2. Will not burn out and will work. In general, forget about Russian details. Throw out KT315, buy 2n7002, the resistors in the base can be removed.
3. R3, R4 - search in Google - "calculation of the resistor for the LED."
4. Power capacity only, but may not be necessary.
5. Nothing will happen. makesystem.net/?p=896 Install a CPC1018n
solid state relay, then the circuit will become smaller.

teleghost, 2014-02-14

thank you, does this mean monitor.net.ru?

teleghost, 2014-02-15

@tugo thank you
! That's just SOT23 is too small for me (my relationship with a soldering iron is worse than that of Lev Nikolayevich with a balalaika ), I would like something that fits without dancing on a breadboard with a step of 2.54 . Maybe there is a larger field worker for the key? I understand, it's like dragging a children's engine with a bulldozer, but don't judge strictly ...
@pr0l , and thank you

teleghost, 2014-02-16

@tugo , I
seem to have found a 2N7000 in the store, and it really should be easier with the long-legged TO92, thanks for the hint (I also only use Google in cases). The optorele still intends to leave KR293KP4B for similar reasons.
the main mat. part will go to the store for a couple more weeks, I promise to report on the layout

teleghost, 2014-02-16

@pr0l , this is a great device, I wish I hadn't seen it before. But the main task is still the serial console over TCP / IP, the dropper is secondary.
Those. in total, you need a serial console, remote reset / power to watch / turn on (watchdog timer, fans, etc. are also cool), costing less than $ 75.
And, of course, the process is important here, someone glues the boats, and I chose electricity :)

teleghost, 2014-02-16

@pr0l , my friend, my desire to play connector wiring for an adequate piping of mikruha, and even more so, the firmware code from scratch is definitely not enough :) the working point is somewhere near the almost finished product for $50-$70 with an open firmware code and a minimum of soldering; then I see already Arduino or just server hardware, where everything is already there without me ...
nevertheless, it's nice to think that I'm not alone, thank you for your support

teleghost, 2014-03-03

Dear dons @tugo and @pr0l , great respect to you, the circuit seems to be assembled on the breadboard (see my microelectronic debut above), at least it responds with LEDs as it should, it remains only to connect it all with the Moch converter and put it into the system. I can't wait for this moment.
hell, this is better than gluing boats! :)) so you can get to the mentioned controller on atmega with a watchdog timer, in any case, I'm already looking for a debug board for the 162nd atmega (so that there is a pair of USARTs) I
dug out, by the way, a fidosh meme: dibr.nnov.ru/n% 3D7381

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