My 38 Khz Squarewave generator circuit for tsop 1138 infrared receiver, doesnot work

[EfeVural]

Hello,

For my lab project i have to setup an infrared range sensing circuit. I will use TK19 105 TSOP1138(i think what is used for tv remote control system) for receiver part. And i have to create a squarewave for after 6 to 70 cycles a gap time of 10 cycles is needed. I setup the circuit attached.. Two different frequencies opamp square wave generator one is 38khz ad other is lower khz.. Then i sum up these voltages then after i put a diot at the output in order to erase negative parts. This way i created the wavelength that is required. However even if i made lots of changes in the circuit i could not properly dedect the square wave with tsop 1138. These devices are broking very easily. Can you advice me how can i idealize my squarewave form and by doing what can i detect this squarewave? I have to use one power supply and elementary materials such as opamps diodes resistors capacitors etc...

 

[Nigel Goodwin]

Sorry, but I've never seen anything like that

The usual method (if you're not using a PIC) would be to use two 555 timers (or one 556). The mixing idea is completely spurious, you need to gate the 38KHz, not mix it.

 

[EfeVural]

sorry i am very beginner level what is to gate the 38khz?

 

[EfeVural]

by the way this is the most general method of whole class. there are some working examples and again we are not allowed to use 555 556

 

[ronv]

It's a little hard to tell from the simulation but it looks like the led may not get turned off all the way. Here is a link to a similar project.
https://www.electro-tech-online.com/threads/range-sensor-urgent.114389/

 

[wkrug]

I would to use a C-Mos 4060 for this function.
It has an internal Clock generator whith requires only a few parts for operation and an integrated binary divider.
One of the Outputs will give the Square Wave of 38kHz, onother Output can be used as Gate.
Mix this 2 Signals with an AND gate will give you a gatet oszillator with 50% Duty cycle.
When other fixed Duty cycles are needed some outputs can be tied together with an AND or NAND gate.
The AND gate for generation of Pulse Packets can consist of 2 Diodes to the gate of the driver FET, or a simple (N)AND Gate like the 4093 to drive the FET.
The 4093 consists of 4 Nand Schmitt Triggers.
Therfore only few parts for that generator are needed.

 

[Ubergeek63]

Hello,

For my lab project i have to setup an infrared range sensing circuit. I will use TK19 105 TSOP1138(i think what is used for tv remote control system) for receiver part. And i have to create a squarewave for after 6 to 70 cycles a gap time of 10 cycles is needed. I setup the circuit attached.. Two different frequencies opamp square wave generator one is 38khz ad other is lower khz.. Then i sum up these voltages then after i put a diot at the output in order to erase negative parts. This way i created the wavelength that is required. However even if i made lots of changes in the circuit i could not properly dedect the square wave with tsop 1138. These devices are broking very easily. Can you advice me how can i idealize my squarewave form and by doing what can i detect this squarewave? I have to use one power supply and elementary materials such as opamps diodes resistors capacitors etc...

9.83Mhz crystal into an HC4060 gives you 38KHz at the Q8 tap. Gate it with the UART output gives you an optical serial data link at 1200BPS.

 

[BrownOut]

It's a little hard to tell from the simulation but it looks like the led may not get turned off all the way. Here is a link to a similar project.
https://www.electro-tech-online.com/threads/range-sensor-urgent.114389/

Yeah man, I agree. Your amps can be slew rate limited, or else have insufficient bandwidth. Look at the spec sheet to determine if they are up to the task. And I don't think your method of mixing the two signals is really going to work. If instead of biasing U3A "+" pins at VCC/2, you used VCC/3, then you would gaurentee that the voltages from the combined opamp outputs switched the amplifier at the desired times. As it is, you don't know if you're switching when, for example, your "slow" signal is high and your "fast" signal is low. But you'll have to make the gain of your last amp much greater. Consider substituting a compartor for U3A.

 

[Ubergeek63]

gate to a FET, amps have no business in this circuit.

 

[BrownOut]

Other things to check:

Is there sufficient drive for your LED?
Is your IR LED the correct wavelength?
Is your oscillator really operating at 38KHZ? You will need to include a means of tuning it.

 

[Boncuk]

May be these ICs are permitted for your project.

For a 38KHz receiver the allowable carrier frequency is 36.1 to 39.9KHz.

This circuit generates a carrier frequency of 38.4KHz.

Boncuk

 

[Ubergeek63]

May be these ICs are permitted for your project.

For a 38KHz receiver the allowable carrier frequency is 36.1 to 39.9KHz.

This circuit generates a carrier frequency of 38.4KHz.

Boncuk

now that looks vaguely familiar