gres
Full Member level 4
Only one task of this system is to checking liquid level in big container ( about 10m3) and display on 7 segments LED indicator.
First idea was to make it at Atmega8 but system has to work all the time throught all year, so chance to hung system was to big.
That's why i made gates system. Iused CMOS gates mostly to make small current consumption. Almost all current goes to display.
The role of transoptors are isolating gates from ferreed switch, that are about 10m away from system and their role is to be a liquid level sensor.
Rectifying diodes has to get BCD code. I used 5410 chipset because it can remember level of ferred switch, after liquid level increase and ferred switch is open. This level is in memory until next ferred switch is bite. System works exactly the same when liquid level goes down. Memory of 4510 system is in 1 PIN, that is steering by 4538 system that consist two monostable multivbrators.
Through selection of elements R22 C1 and R23, we can set time of signal generating by multivibrator. Here times are long (0,5-1 sec) because of kind of vibrator.
Liquid level increase very slowly ( between close first ferreed switch to second takes about 1 week), such a long times guarantee system resistance against contact vibration.
All system is placed in not very attractive casing, but it's install at garage wall.
At : https://www.elektroda.pl/rtvforum/topic1445147.html you can find original text, diagram in PDF and SCH also pcb project in PDF , PS scale 1:1 printable in Corel.