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Saturday, October 18, 2014

Presettable Up-Down Counter Timer

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.

I made some modifications and sent it to him, that helped him with his task. These things can be done very easily using the Arduino. One could make a programmable Arduino Timer/Counter with a matching Configuring Software without coding, for such people. Easy and Affordable.

Digital Circuits 2 from delabs

Circuit 1 - Digital Timer Clock With Preset using Thumbwheel switch.

A Thumbwheel Switch has to be used in place of DIP switch shown, just know that 1-2-4-8 nibble (4 bit) should be generated by Thumbwheel switch at preset or jam inputs of 4029.

Use CD4511 if 4513 is not available, but circuit has to be changed a bit around 4511


Circuit 2 - 1 Hz or 1 pps crystal clock using CD4060 and 32768 Hz Crystal.


They have not been tested much... The 4513 control pins 8-4-5-3 connections verify, as i did not get the datasheet.

The circuits will work as the concepts are right, but some tweaks in R C values may be required.
the R C values can only be corrected if you have problem in making it work.

The main problem in the R C values may be related to "the reset at 6 for the tens of seconds and the tens of minutes".

Wednesday, October 15, 2014

Music Sound to light converter

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.

Music Sound to light converter

The voltage across the speaker is fed to C1-Gnd, which blocks DC component. R1, R2, R3 form a threshold bias for T1. 2N2222 chops the 12V DC in tune with the music.

Basics of Electronics

The chopped DC current flowing in the 12V winding of TR1 is stepped up into AC pulses over 100V, this lights the Neon in flashes synchronizing in real-time with the beats. Known Issues - It does not perform well at low Bass like 20Hz.

Tuesday, October 14, 2014

Simple Water operated relay

This was done in my early days, i have upgraded it, it ought to work, reduce the number of transistors to make it less sensitive, also a lower value in place of 10M will reduce its sensitivity, use clamping diodes to protect.

BD139 is used to drive the relay as it has good Ic. So you can even use a low ohm relay. If a Relay resistance is high its quality is higher, its power consumption is less and it needs thinner wire SWG-AWG. T2 and T3 form a darlington pair which drives T1. LED1 shows that the water level has reached the top of tank and also that the Relay is energised. D1 a freewheeling diode. R3 10M ensures that the high gain input does not float, yet the low leakage current thru the water is not drawn away by the 10M. R2 limits base current in case water is saline.
Simple Water operated relay