The data outputs ARE latched, they stay set even after the input tones are removed.
The strobe output is momentary and only present when a valid DTMF signal is being decoded.
If you want the output to be present only when a tone is heard, you need to logic AND the latch outputs with the strobe signal.
Brian.
Dear Mr.Brain,
Thank you very much for your above reply.
As per your explanation I have checked and confirmed followings,
(1)Q11-to-Q14 BCD outputs are LATCHED when valid tone decoded. And stay high until next tone /BCD code recived.
(2)Std (Pin no.15 of MT8870) high Momentary when valid tone received/decoded.
Now I am facing following problem,
(1)
I have connected D flip-flop (IC 4013) at one of the output (say pin no.11) of MT8870 to CLK of (IC 4013). But as the BCD output of MT8870 (pin no.11) is continuously high and doesn’t change its state when same key is pressed simultaneously to turn on/off appliances, as a result CD 4013 output also gets unchanged.
In other word, when the same key (suppose 1 from DTMF tone generator) pressed (to turn on the appliance) CD 4013 output LED glows and again pressed to turn off the appliances D- flip-flop doesn’t change its state. (as the BCD code in both cases is 0001 keeping CLK high only). REQUEST TO PROVIDE PROPER SOLUTION.
(2)
When I switch on the power of the DTMF receiver circuit(IC MT8870), a random output at LEDs (connected at BCD output of MT8870) glows. Hence I guess, if I connect relay to control appliances gets on randomly when circuit powered on.
Below find sketch of circuit for better understanding.
View attachment Remote Control.bmpKindly help me out… plzzz..
And also provide if you are having any simple 4 Channel Output Electrical Appliance Control Circuit.
Ones again thanks for your quick help……
Awaiting for your reply….
Regards,
T.D.