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??? am very much interested in building this transistor tester project of which the author i believe is randy linscott as you have presented. however, before i do so, i would like to clear up some doubts,
1. is IC4027 a dual JK master/slave flip flop w/set-reset?
2. where can i find the datasheet for this ic
3. is pin 1 & 2 open or not used?
4. is the output of the 555 (pin 3) connected to pin 12 of the 4027?
thank you in advance for whatever info you can give me.

Project Link: http://www.electronics-lab.com/projects/test/008/index.html

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??? thanx for the datasheet you sent. however a good friend also sent me datasheet on this chip made by fairchild semi. CD4027BC. the one you sent was CD4027B by texas inst. i have seen both internal circuitry and each one differs. the BC type use single inverters while the B type uses 2 series inverters. is this output critical to the sensitivity of the tester? which one do you recommend. again thanx! :D

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The best way to hanlde electrostaticly sensitive devices is to supply your work bench with an antistatic mat which is connected to the ground. Also you must discharge yourself. For that reason use a conductive wrist connected to ground. There are special Antistatic Work Surface Kits and equipment like below:

But in case you what to handle electrostatic sensitive devices occasionaly and don't want to buy any special equipment, follow the rules below :

1. Don't handle CMOS circuits directly.
2. Avoid touching metal leads and other circuit areas when handling devices with CMOS parts.
3. Discharge your hands by touching a fount.
4. Try to handle CMOS from it's case.
5. Use a pincer to install the cmos, which you have connected to the ground.

If you follow these rules you can install it succesfully. Keep in mind that cmos can be installed succesfully without following any of these rules if you are lucky, but these rules will reduce the chance to damage it.

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:) sorry if i sound too naive about handling cmos.
1. how about if i have to align the pins to the socket, what do i use to straighten the pin. someone advise that i can use a long nose plier provide the plier is insulated and i dont touch the pin directly, also they say i dont have to worry about electrostatic energy here in the Philippines bcoz we have humid weather here. Is this true?
2. my workbench is made of wood and also have wooden floor.
3. do i have the plier attach to a ground?
your reply would be highly appreciated. thaanx in advance!

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mozikluv you and your questions are always welcome :) !

1. Attach the plier to the ground for some seconds to discharge it. Handle it from an insulated grasp. Then align the pins without fear. If you want to feel more secure attach the plier to the ground via a cable, but i think it's not quite necesarely. The weather also helps if it's humid to have less atmoshpere charges.

2. I don't know about wood, but it's surelly better than having a moquette or carpet ;D !!

3. See -> 1

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  • 4 weeks later...
  • 1 month later...

[Hello there and thankyou very much for the reply to my question but can you please confirm that the diodes D1 to D4 are connected to pin 15 via the R3 resistor exactly as shown in the schematic diagram can anyone help resolve this question ? as I am up the creek without a paddle becuase the diagram does not look right somehow I need to know the answer to my question before I can attempt to biuld this project ???

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Hello Electronicslady.
Welcome to Electronics-Lab community :)

Pins 10,11,16 connect together and to the rest of the circuit.
Pins 3-9,13 (3,4,5,6,7,8,9,13) connect together and to the rest of the circuit.
Hello again I'm still trying to build this circuit and still not getting anywhere and I keep trying to get it to work but I think I've got the pinouts wrong because I'm only getting one led to light and that's lit all the time but does not flash.
This is what I've tried now I've got pins 3 to 9 and 13 of the IC 4027 all connected together and onto the neg rail and I've got pins 10 and 11 and 16 all connected to the plus rail.

I would be very pleased for any help that you can give me about this circuit as I'm new to this site and I've not yet managed to get this one to work so far.

Thank you
from Jennifer
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  • 3 weeks later...

hi ,, thank u very much for reply... :D,,the problem now is that i've only one led lighting not flashing....what do u think is wrong?

I would be very pleased for any help that you can give me about this circuit as I'm new to this site and I've not yet managed to get this one to work so far.

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You can check if 555 is ok by measuring the output pin 3. It must has a 12Hz signal. To do that you must have access to an oscilloscope or a digital multimeter that measures frequency. Alternativally you can replace 555 to be sure it's ok. Keep in mind that the most common problems are at the connections. Double or triple check them in different moments in a day so your mind is clear. Also make sure you really understand the connections reading the schematic and there are not confusions.

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