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Cd4033 - 555 timer frequency counter..

ian moree

Mar 6, 2017
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Good day everyone;

i have built this circuit and no matter what i do, i am unable to read frequencies from known sources.

Perhaps the circuit itself is incorrect? i would appreciate any guidance one has to offer.

thank you

-ian

upload_2017-3-6_12-48-47.png
 

Alec_t

Jul 7, 2015
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Welcome to EP.
I see nothing obviously wrong with the circuit.
Are the displays showing anything?
Is your input signal amplitude at least 1V?
Check that :-
pins 16 of all 4033s are at the correct supply voltage,
pins 3 of both 555s, and the collectors of T1 and T2 are all toggling.
 

davenn

Moderator
Sep 5, 2009
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Hi Ian,
Welcome to EP :)

Good day everyone;

i have built this circuit and no matter what i do, i am unable to read frequencies from known sources.

Perhaps the circuit itself is incorrect? i would appreciate any guidance one has to offer.

thank you

-ian

where did the circuit come from please link to it ... so we can see any circuit descriptions etc


Dave
 

ian moree

Mar 6, 2017
6
Joined
Mar 6, 2017
Messages
6
Welcome to EP.
I see nothing obviously wrong with the circuit.
Are the displays showing anything?
Is your input signal amplitude at least 1V?
Check that :-
pins 16 of all 4033s are at the correct supply voltage,
pins 3 of both 555s, and the collectors of T1 and T2 are all toggling.

DIsplays are Showing all Zeros
signal amplitude is 2.163 volts
correct 5.5v at pins 16,3 on 4033
**dont know how to test T1 , T2 toggle
 

ian moree

Mar 6, 2017
6
Joined
Mar 6, 2017
Messages
6
Analog OScope, Digital Multimeter(fluke, and more ), sinometer, LC METER,

The led's are lighting up but not blinking.
 

Alec_t

Jul 7, 2015
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LED1 and LED2 should be flashing alternately, with a period of ~4.6S and an 'on' time of ~2.3S. As this is not the case, check all pin connections to both 555s and ensure they are getting 5V on pins 4 and 8. If the 555s are socketed, make sure you have the ICs the right way round in the sockets.

Edit:
This probably has no bearing on your immediate problem, but one thing I don't like about that circuit is that when pin 3 of IC2 goes low, cap C6 applies a negative 5V pulse to pins 15 of the 4033s. I'm not sure they'll like that. Personally I'd clamp that pulse with a diode (anode to ground, cathode to C6/R12 top).
 
Last edited:

Audioguru

Sep 24, 2016
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The old 555 ICs draw a 400mA spike from the supply each time they switch. Therefore the datasheet spells out two very important supply bypass capacitors that are missing in this bad circuit. I think Cmos 555s should be used.
 

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ian moree

Mar 6, 2017
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Unfortunately , this is the only schematic i can find with components i currently have. If any of you have another schematic which can help me, then that would be awesome. Thanks with everything. will check...
 

Audioguru

Sep 24, 2016
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Simply look at the datasheet of the 555 and order and connect the supply bypass capacitors that are recommended.
The old project in the Electronics For You website is from India.
 

ian moree

Mar 6, 2017
6
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Mar 6, 2017
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I took out and tested every IC -4033 & 555 timers and 2 out of the 5 4033's in circuit came from Mouser Dead. Thanks for all your help, now that i have functioning 4033's the circuit works flawlessly with bypass caps for pins 4 & 8 of the 555 timer connected. thank you all for your help!!
 
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