using HT12E and HT12D with varying supplying voltage

[arunkumar413]

Hi friends,

I'm trying to build a wireless system using HT12d and ht12e. From their graphs I understand that oscillator frequency changes as per the supply voltage. In my case at the encoder side the voltage varies from 1.5v to 3v (AAA batteries) and at the decoder side the voltage varies from 12 to 9v (12v automotive battery). In this case how to ensure that the frequency remains stable so the circuit operates.

Thanks
Arun

 

[4pyros]

Use voltage regulators or DC to DC converters to power the chips off your battery's.

 

[arunkumar413]

That would make the circuit more complex. Though we use dc-dc converters, there may be slight variations in the voltage at the decoder and encoder side. In this case does the overall circuit remains stable? Is there any work around to make the oscillator frequency independent of the supply voltage. As these ICs are mostly used in remote controlled applications which are powered by independent voltage sources. Making the frequency dependent on supply voltage isn't a good idea at all.

 

[arunkumar413]

data sheets of the ICs in question
**broken link removed**
**broken link removed**

 

[4pyros]

The oscillator has nothing to do with the RF frequency.
The oscillator frequency is not that critical just one has to be faster than the other.
Just use 3 volts and 12 volts for the resistor calculations.

 

[audioguru]

The simple very old remote control ICs were used many years ago in cheap remote controlled toy cars and boats. They did not produce proportional controls, instead they had bang-bang steering which was full left, center or full right. It also provided bang-bang speed which was stop, go and reverse.

 

[Nigel Goodwin]

The simple very old remote control ICs were used many years ago in cheap remote controlled toy cars and boats. They did not produce proportional controls, instead they had bang-bang steering which was full left, center or full right. It also provided bang-bang speed which was stop, go and reverse.

You've lost the plot AG

The IC's under discussion are for simple IR or Radio remote control, as used for a TV set or similar - NOT for radio controlled models.

 

[4pyros]

You've lost the plot AG

The IC's under discussion are for simple IR or Radio remote control, as used for a TV set or similar - NOT for radio controlled models.

They could be used for "Bang Bang" RCs.

 

[audioguru]

You've lost the plot AG
The IC's under discussion are for simple IR or Radio remote control, as used for a TV set or similar - NOT for radio controlled models.

The OP has a remote encoder and a car battery in the (model?) car. Some of the cars in his country are tiny and so are the car batteries.
Google Images of these Holtek ICs shows switches at the encoder and relays at the decoder.

 

[Nigel Goodwin]

They could be used for "Bang Bang" RCs.

Too slow to do that, again it's for simple ON/OFF switching as per a TV remote etc.

 

[audioguru]

"Bang bang" remote control of a model car is slow. When a button is not pushed then the car steers straight. When the Left button is pushed then the car suddenly turns sharply to the left. When the Right button is pushed then the car suddenly turns sharply to the right. It might do a gradual turn if you quickly push a button on and off many times (finger-width-modulation).
Speed control is the same, no speed (stopped), slow speed or another button for full speed and maybe also another button for Reverse.

 

[4pyros]

(finger-width-modulation)

Would not that be fingertip-width-modulation?

 

[audioguru]

You can poke the pushbuttons with any body part that sticks out!

 

[4pyros]

I get better resolution with my middle finger.

 

[audioguru]

I get better resolution with my middle finger.

I have never raised my middle finger.
My middle finger is the longest so I use it to push the station buttons on my car radio.