Some old examples of open custom designs. these were made to educate the customer and also study the capability  of online communication and and collaboration tools for such activity.  **Two Stage Sequential Timer Docs -** \ \ The circuit is a two stage sequential timer with auto reset. It can turn a Solenoid On/Off after a Sequence of delays that are preset. This is also a basic example of timer usage in automation.\ \ **Design Documents** - [Discussion of Sequential Timer - A](https://www.delabs-circuits.com/cirdir/service/2004-2006/doc00035.html) - [Discussion of Sequential Timer - B](https://www.delabs-circuits.com/cirdir/service/2004-2006/doc00036.html) - [Sequential Timer Specs.](https://www.delabs-circuits.com/cirdir/service/2004-2006/doc00033.html) - [Two Stage Sequential Timer.](https://www.delabs-circuits.com/cirdir/service/2004-2006/del90004.html) - [Li-Ion Battery Charger.](https://www.delabs-circuits.com/cirdir/service/2004-2006/del90005.html) All Timers are 1 - 30 Secs Analog with Presets to adjust with a screwdriver. The Switch, Solenoids and Power supply has to be via terminal blocks or plug-jacks. The PCB may be upto six Square Inches for standard DIP components but with SMD it may be smaller. **Four Channel Temperature Alarm Docs**\ \ The temperature in a pipe is monitored with four RTD Pt-100 Sensors, The type of probe could be Extruder RTD probes with Bayonet or Compression Fitting, Get it from Omega. To keep costs low you can choose small thin film RTD sensors, they will be fast but on rough usage may break.\ \ **Design Documents** - [Discussion of four Channel Alarm.](https://www.delabs-circuits.com/cirdir/service/2004-2006/doc00034.html) - [Four Channel Temperature Alarm.](https://www.delabs-circuits.com/cirdir/service/2004-2006/doc00032.html) - [RTD Pt-100 Four Point Alarm.](https://www.delabs-circuits.com/cirdir/service/2004-2006/del90001.html) - [Timer and Counter Modules.](https://www.delabs-circuits.com/cirdir/service/2004-2006/del90002.html) The time taken to measure the temperature at the 4 points will be less than 4 seconds. An optional display of the measured temperature as shown above can be avoided by using a DMM to adjust the setpoint.\ \ The Analog Timer Module can be set from 0- 30 minutes. If out-a remains high even after set time a out-b alarm goes on to sound a buzzer and flash a LED light.