Two Sets 10 channels O'scope and Multimeter Multi-Inputs Selector.

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Joined Aug 23, 2012
Two Sets 10 channels O'scope and Multimeter Multi-Inputs Selector --

Two rails of O'scope can be measure 20 points, or single rail can be measure 10 points and using another multimeter to measure 10 points.

O'scope And Multimeter Multi-Inputs Selectors :

This multi-inputs selectors was designed to measure many points of the circuit, the voltage level is 0 to 5V or logic pulse, I also drew a 40 channels monitoring points based on single-chip controller as 8748 long time ago, but I haven't complete it, actually is too lazy, and this two sets of pure logic circuit 10 inputs channels completed first, but this circuit was designed at about 21 years ago(1995), I were putted it in the box without completed until 8 years ago sorted out and found out the problems, complemented part of the circuit which wasn't completed, and finally the function was worked normal, the Vcc was provided by +5 V power supply, it can be changed to add a 7805 with 9V battery, the total quiescent current consumption less than 20 mA, almost the power consumption focus on NE555 and LEDs. 

Certainly, you may not use this circuit, and replace the electronic switches by using 20 normal push switches, if you do not use this function, study this circuit also could guide you to use CD4066 and CD4017 composed of the electronic switch selection have a better understanding, and to apply it in your circuit.

About the circuit diagram is not complicated, look the drawn block diagram, you can understand that it is easily, to choosing the detection point, you could press A or B key once to select a point (channel), or to press and hold it to let the 555 square wave to send the pulse directly to CD4017, this method is the same with the current input function of computer keyboard, CD 4017 is a counter divided by 1 to 10, to select its desired point, and to control the control pin of 4066 corresponding to the electronic switch, to turn on the inputs of multi-points and then select a point A or B of oscilloscope or multimeter.

Sw1, Sw2 select the number of input points, it was added to the list after this tester completed, this function can used to the measuring channels less than 10 points, it can be speed up the cycling speed of CD4017, of course probably you won't use it.

Between the voltage input terminal and the output waveform, it may has a little difference, because the internal resistance caused that by CD4066, but it does not affecting the function of selector.

▽ 1. Oscilloscope and multimeter multi inputs selector block diagram --

▽ 2. The practical circuit diagram -- the output LED indicator of CD4017 already improved with only a common resistor, because at the same time only one LED will lighting up.

▽ 3. Entire PCB components and Case only placed on the box -- but I didn't use screws fixed it)
10 pins connector was took from other instrument that it was a old logical analyzer.

▽ 4. Labeled the function for each block -- the practical assembly, because it was soldered a long time ago, so the output (beside the input LED indicator) of CD4017, it was still using the old circuit, each LED with a resistor, but the new circuit diagram, only sharing a resistor.

▽ 5. PCB solder side -- because the circuit have been modified, the added parts and wiring a bit messy.

▽ 6. Input Terminal 10 pins x2

▽ 7. Homemade IC socket Connector (IC socket welding pin, 10x1 2 rows)

▽ 8. The inputs terminal can be use different connectors -- such as: double-pin connector or IC socket or your own favorite way.

Designed by Scott Wang.

Scott Wang's Blog.