HEF4514 or CD4514?
What is EL and E bar in the attached data sheet of HEF4514?
How to connect HEF4514 to the MT8870 BCD latched output to switch on / off the appliances.
Whether HEF4514 has a latched out out or momentary?
it is right to connect D flip flop in toggle mode at the out out of HEF4514 for on / off application of appliances?
Regasrds,
T.D.
The outputs are all low if 'E' is high so you must pull it low if you want anything on the output pins.
'EL' enables the data into the latches when it is high and holds it there when it goes low. You can connect it to the 8870 'Std' output so you get one of 16 outputs which go active (high) when a DTMF tone is received and stay active until a different tone is received.
Brian.
Dear Brian,
Based on your above explanation, output of HEF4514/CD4514 is staying active until a different tone is received.
(Q) Now, what happen if I press 1 two times simultaneously once to switch "ON" the appliance and second time to switch "OFF" the appliance. (Refer circuit for more clarity). MT8870 + HCF4514 + 4013.bmp
As the output of HCF4514/CD4514 is connected to IC4013 (D Filp flop in toggle mode). I suppose to toggle ON/OFF.
Waiting for your relay?
And Happy new year to you and your family?.
Regards,
T.D.
There is no way to tell if the same tone is sent twice as the output from the decoder will stay the same. what you are trying to do is use the same tone repeated to do two functions, on and off.
The only way is to count the number of times the strobe signal occurs with the same digit pressed so yes, a D flip-flop is a good solution. You can wire it as you show in your schematic but you should also connect the 'E' input of the 4514 to a logic high so the outputs are enabled.
The problem you might see are that although the output of the flip-flop will toggle each time the same tone is sent, you have no way of telling which state it is when the power is turned on. You can wire a reset circuit but to be honest, your best solution is to use a small micro. It will let you do much more, will use fewer components and will cost less.
Happy new year to you and your family and to anyone else reading this!
Brian.
Dear Mr.Brian,
Thanks for your best explication.
As explained by you, I?m facing the exactly same problem as stated by you.
(1) Now I am getting on and off function while pressing the same key from DTMF generator. But the problem is when I switch on the power of circuit, LED connected at output of D flip flop (in toggle mode) gets ?ON? randomly. (Which is not desirable to control home appliances remotely)
(2) Till now I have connected DTMF (UM91214B) output directly to MT8870 (DTMF receiver) input. But now I?m trying to transfer DTMF tone via IR LED and
I connect TSOP1738' (at DTMF receiver) but it just not happening. (If possible, please guide me for connection of IR LED at DTMF generator and connection for
IR receiver module(TSOP1738') at DTMF receiver)
After most frustrating experience with this circuit, and as advised by you to try small micro.
I want to try out that, but problem is, I don?t have any circuit diagram. If you are having any remote controlled home appliance remote circuit for home appliance control (min. 4 channel) please please please forward me, I will be heartily thankful to you?.)
Regards,
T.D.
You can not transfer the tone by IR, the way it works is completely different.
DTMF is two analog tones, one tone tells which column on the keypad the key was on and the other tone tells which row. Decoding is done by filtering and detecting the two frequencies then converting the result to a binary number.
IR transfers the binary data one bit at a time in a serial stream so no tones are used. It is not as simple as just flashing an IR LED though, doing that would make it very unreliable because the receiver would respond to any changes in IR light it could see. IR sources include lighting, hot objects and remote control units, all of these would cause interference.
The TSOP1738 is an IR receiver with a built in 38KHz filter. The reason 38KHz is used is to make it easier to prevent other interfering IR sources being detected. What you have to do is send your key data as a binary number, the binary '0' is sent by turning the IR LED off and the binary '1' is sent by pulsing the LED at 38KHz rate. There are two other things you must do, first is to send a long burst of 38KHz (for about 10mS) just before the data so the TSOP1738 can adapt to the signal, second is to format the data so the receiver can work out which data bit it is seeing.
It is not easy to convert DTMF to IR, I suggest you start again using one or the other but treat them as completely different ways of transferring data.
Dear Mr.Brian,
After long and frustrating experience with this DTMF transmitter-receiver remote control 4 channel appliance control circuit, I leave off the hope and this project.
Requesting you to provide me a complete circuit diagram for remote home appliance control project.(both Tx & Rx)
I will be very very very thankful to you for above ?.plzz help me?
I heard about Phillips RC5 remote control transmitter and receiver can also be used to control home appliances remotely. Is it right? Is there any circuit for the same? plzz provide...
Awaiting for your valuable reply!
Regards,
T.D.
The trouble with remote controls is they are different for every appliance, there is no true "universal" system.
I wrote a short article on IR works a few years ago, you can find it here: ATV-Projects Infra Red Remote Controls
It does not have circuits but it explains how they work, I hope it is useful.
Dear Mr.Brian,
As I leaved-off the 4 channel remote control project using DTMF tone.
Now, I moved to 4 channel remote control project using HT12E and HT12D pair.
Project circuit and data sheet of HT12E and HT12D attached for better clarity.
Remote Control Circuit Sketch.bmpht-12a.pdfht-12d.pdf
I had connected HT12E and HT12D as shown in sketch. (Only thing is currently I had connected HT12E Dout to Din of HT12D directly for testing purpose only.)
I?m facing following problems,
(1) As indicated in data sheet, to transfer the data I suppose to ground ?Bar TE? and the desired data pin to Vss (through switch suppose SW1). After doing this, data gets transferred to HT12D. LED connected to VT (pin no.17) of HT12D glows. Now problem is LED-1 connected to Data output(D8) of HT12D is gets ?OFF? (instead of getting ?ON?), while pressing other data switch (suppose SW2) on HT12E, data gets transferred (VT LED glows) but corresponding(D9) LED-2 at the HT12D gets ?OFF? (instead of getting ?ON?) and rest of the LEDs(LED-1,3,4) connected to other corresponding data output(e.g.D8, D10 & D11) of HT12D gets ?ON??..
Kindly provide me solution??.
Regards,
T.D.
You seem to be trying lots of different methods instead of fixing the problems with the first one!
Yes, 'Bar TE' must be at low logic level before any transmission can take place.
You should connect all the address pins of both modules to some logic level, it can be high or low but the same combination must be used on both modules.
Be careful to check the amount of current you are taking from the output pins to the LEDs, the decoder does not have high current drivers, it is only rated at 1.6mA.
The outputs are not latched, they should follow the voltage present on the transmitter data pins.
Dear Mr.Brian,
I had kept all address pins of both HT12E & HT12D at same logic only.
But what will be probable reason for following problem which I?m facing;
(1) When switching SW1 on Transmitter (HT12E) (along with ?Bar TE?) the same is receive (VT gets high) and corresponding LED-1 connected to (HT12D) gets ?OFF/LOW? (instead of getting ?ON?) and rest LEDs(LED-2,3,4) gets ?HIGH/ON? ?
(2) Now, While switching other data suppose SW2 (along with ?Bar TE?) on transmitter (HT12E) the same is received (VT gets high) and corresponding LED-2 connected to (HT12D) gets ?OFF/LOW? (instead of getting ?ON?) and now rest LEDs(3,4) and LED-1(which is ?LOW? in first case) gets ?HIGH/ON? ?
Awaiting for your precious reply?
Regards,
T.D.
To be honest, I'm not sure what is wrong. I have never used these devices so I can only guess at the cause. Whenever I send serial data over an IR or RF link I use a microprocessor to encode and decode the data.
It seems strange that some data is getting through but not what you expect it to be, if the problem was a wrong address it wouldn't work at all. Possibly the oscillators are too far away in frequency and you have framing errors. Please try all 16 different logic levels on the data inputs and record the outputs for each so I can see if there is a pattern to them.
Brian.