Schematics of delabs

When i had put the near Obsolete digital circuits online in the late nineties. One person who works in a public institution in the usa, wanted a modification of one of my existing circuits. He had those parts the CD40 Series Logic Chips. He wanted to use only those that he had in his Stock.

Digital Circuits 2 from delabs

I made some modifications and sent it to him, that helped him with his task. These things can be done very easily using an embedded microcontroller. One could make a programmable Timer/Counter with a matching Configuring Software without coding, for such people. Easy and Affordable. You could also make a pure digital chip by using a CPLD or FPGA, if that is affordable.

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The Early Microcontroller : 80C39 is a CMOS Version of 8048 the one that preceded 8031-8051. MCS48 is the set for that, MCS51 is the current set.

Process Controller code here 80C39 Code for MCS48

Digital to Analog Converter with uC Watchdog is the front end and an external  hardware watchdog of an early kind. These are simple but robust circuits and worked well in noisy environments.

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This is the continuation of the earlier post. Part of 80C39 based Process Controller. In this schematic you can see the Watchdog and D/A Converter.

80C39 and MCS48 based Process Controller is the main circuit that has the LED 7 segment display for output and push keys for input. The old form of Human Machine Interface - HMI.

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The Circuit below is a paper design and not tested. It can be used for education and information, this can help you make your own design. Please do not just wire it up and expect it to work.

Regulated High Voltage Power Supply - del20032

Now let me see if i can explain the circuit, This is a regulated AC power supply. This circuit uses the Mosfet to turn off when voltage goes beyond a reference point. That means it just chops the Sine wave above a point, that also implies that the output may not be pure sine and may have harmonics. The Transformer if well designed may smoothen the chops. Even a Series Inductor or Resonant Circuits may reduce harmonics.

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This was made by me when i was a kid, it was even published in a magazine, i think it will work, it was used on a very old huge ornamental valve philips stereo system in the remote speakers.

Home Made Circuits

Recently i captured this circuit in eagle to publish online, it seems to have a small design error. It worked well for many years. The step-down transformer is used as a step-up here. The secondary winding was around 50mA so the resistance was protecting the 2N2222. (SL100 was used in the original one). C1 and R3 may need tweaking to get the desired adjustment range in R2.

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