initial jung o/p of dtmf receiver

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grittinjames

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hai
i had made a remote control using dtmf . but how to make o/p of 8870 to 0000 on power up . it is giving jung values on power up
 

grittinjames said:
hai
i had made a remote control using dtmf . but how to make o/p of 8870 to 0000 on power up . it is giving jung values on power up
Click to expand...

What are you babbling about. I don't understand what you're saying.
Please re-state your question in a clear to understand format.
 

hai meridian
u will not be knowing about mt 8870 ic

it is a dtmf receiver . when u power up this ic it will give some error o/p.
is it possible to reset with out giving a dtmf input
somthing like power on reset
 

grittinjames said:
hai
i had made a remote control using dtmf . but how to make o/p of 8870 to 0000 on power up . it is giving jung values on power up
Click to expand...



As you have written I think there is a solution , and for that you need to generate the same twin frequencies for D at the input of the MT8870 . You can use two crystals to do it .
 

hello friend
think proficiently . we will not get crystels with frequency of our requeremet.

it is not economically practical to spend cost of two crystal for resetting :!:

i think ur answering just for points


 

1.) Did you check pin6 PWDN pin ?

2a.) Connect diode to each of the output pin then connect them to transistor collector.

b.) Add a RC delay during power up so that the transistor will switch on for a defined time. The purpose is to short the jung output signal to gnd during power on.

Please check whether it can solve your problem or not

Rogerynt
 

hai rogerynt
after some time that is transister turn off this junko/p will again .this circuit is not clearing the latch
assume on power up o/p is 1111 .for a short time o/p will be able to maintain 0000 as per ur circuit forgetting loding of ic.after that this 1111 used for switching some appliance it will turn on.
this will not be knowing tx . wt i shuld do

right now i kept a battry back up .this also having several disadvantage
 

Hi,

Do you mean the ic will send out jung periodically ?

If the ic sends jung only at power up moment then the RC delay will cause transistor to switch on for a short period of time. Therefore, the pin diodes are pulled to gnd by this transistor and hence the jung data come out from this pins are shorted to gnd. Once the transistor switches off, data come from any one of these pins shouldn't interfere the others because the diodes are in reverse bias. ( Therefore, signal can't goes to the other pins )

Rogerynt
 

hai rogeryth
thanks for ur analysis. my project is remote control. this circuit is coming at receiver side.
as u think ic is not sending data periodically . in power up it it generate some data . it will latch upto next data comes. ur circuit will not help in clearing this lathch.
after transister off this data will exits still
 

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