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???
03/01/06 10:37
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#110962 - analysis results
Responding to: ???'s previous message
Kai Klaas said:

Try to find out how the circuit works - by yourself. Make an analysis of the circuit and post your results here. And - you should at least spend as much time as I did...
Kai


This is what i got from the circuit.

Kindly let me know about the mistakes i have done:

Trigger input connection:

The 10k and 1uF forms a differentiator network which delivers positive and negative going spikes.
The diode is used to limit the amplitude (by becoming frwd biased) at trigger i/p to .7V during the positive going spike.
This .7V flow to the RC network 1K / 10nF.( - Kindly give me few info to know the use of this RC network)

Reset pin connection:

The reset pin is also connected with a similar difftr network with voltage limiting diode. Here the reset pin receives .7V (typical value for device reset when current through it is .1mA)

- I need to know how the flow of current through the reset pin is calculated when using such RC network.
Is just applying ohms law enough = V (source vol) = I*220K
I = 5 / 220K (Since current through cap decreases with increase in its charge )

Comments needed.

Lastly regarding that transistor Bc550,
i could only find that it will be 'ON' for the time delay i will be setting with the Pot.

when the SW is depressed continuously:

Also referring to the abnormality curves (that happens when the SW is depressed continuously) discussed before, i could only take it in a way that 'the Transistor is doing the same job as that of the switch (either one is going to ground the cap) connected parallel to it when the Switch is depressed continuously..
So iam unable to come to a conclusion on how it rectifies the problem of abnormality.

giving some hints could help me know about it.

Thanking u,
suresh.


List of 39 messages in thread
TopicAuthorDate
Pressing 555 trigger SW continuously.            01/01/70 00:00      
   Again            01/01/70 00:00      
   capacitor couple it.            01/01/70 00:00      
      Re: cap coupling            01/01/70 00:00      
         Look up the internal block diagram            01/01/70 00:00      
            Read the Data Sheet!!            01/01/70 00:00      
      got the o/p            01/01/70 00:00      
         Satisfaction            01/01/70 00:00      
            Thanku steve            01/01/70 00:00      
         Not enough            01/01/70 00:00      
            alternatives ?            01/01/70 00:00      
               Remedy            01/01/70 00:00      
                  remedy?            01/01/70 00:00      
                     Alternatives            01/01/70 00:00      
                  BC550 & diodes            01/01/70 00:00      
                     Try it by yourself, it's simple!            01/01/70 00:00      
                        analysis results            01/01/70 00:00      
                           Analysis            01/01/70 00:00      
                              Thank you            01/01/70 00:00      
                              after the set delay Time            01/01/70 00:00      
                                 Enhanced debouncing            01/01/70 00:00      
                                    What do you think about it, Suresh?            01/01/70 00:00      
   why the neqw thread            01/01/70 00:00      
      reply            01/01/70 00:00      
         Read the Data Sheet!!            01/01/70 00:00      
   kalpak dabir            01/01/70 00:00      
   Have you considered using a 74121?            01/01/70 00:00      
      74121 versus CMOS555            01/01/70 00:00      
      74121 fine for short period delays?            01/01/70 00:00      
         No debounce needed???            01/01/70 00:00      
            Schmitt trigger operation?            01/01/70 00:00      
               Transition times of input signal            01/01/70 00:00      
                  controlling noise related issues            01/01/70 00:00      
                     Schmitt-trigger operation            01/01/70 00:00      
                      CD 4541BC = Alternative for ICM 7555?            01/01/70 00:00      
                        Do you really need to build it?            01/01/70 00:00      
                           Yes.            01/01/70 00:00      
                              try try try again            01/01/70 00:00      
                                 a sign of confidence            01/01/70 00:00      

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