I am trying to do the circuit

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In summary: In the transmitter circuit, T1 base appears to fed with a relatively large audio signal without any added DC bias. I believe that this is likely to give a grossly distorted result - are you certain that this has been drawn correctly?The transmitter circuit is correct, but the receiver circuit is not. The receiver circuit is missing the capacitor at C1.
  • #1
diegovishnu
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i am trying to do the circuit "www.electronicsforu.com/efylinux/circuit/.../aug99_IRcordless.pdf"[/URL]
the phototransistor showed in the circuit has only 2 leads but the 1 i brought has 3 leads with a number 1838 written on the top..
please help me what to do. even if i brought a new 2 lead phototransistor, how to find the emitter and collector?

also please help me with the audio output transformer. I am not getting it anywhere in the shops
 
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  • #2


That link doesn't seem to work.

However the device you have may be a TSOP1838
Here is a data sheet for it:

http://pdf1.alldatasheet.net/datasheet-pdf/view/26604/VISHAY/TSOP1838.html

If it is that one, it needs a pulsed signal at 38 KHz to work. Almost any domestic remote control should give some results with it.

That data sheet does not give the pin connections, but the following image is better.

images?q=tbn:ANd9GcQ56MJn-mAu-aMZmteQJ7Zy79Wu_pUMvpDO7EpzMf-_QPuT1LgdMg.png
 
  • #4


No, if this device you have is the TSOP1838, then you can't really use it as an optical audio receiver. They are meant for remote controls.

If possible, take it back and exchange it for a proper photo-transistor.

Be careful also not to get a light dependent resistor. These are Cadmium Sulfide cells and have a very poor frequency response.
 
  • #5


i brought 1 phototransistor.but its not semicylindrical as the circuit say..its a blue 1 which looks similar to an LED.
you told the circuit may not work. can you clarify on that?
thankyou in advance
 
  • #6


diegovishnu said:
it will not work?

No, your first link did not work. Next, No, the part you bought is an integrated circuit not a "straight" IR photo transistor. The part you bought includes a circuit to make it easy to use as an IR detector for a remote control, which uses a pulsed IR signal, and decodes it. (Changes the pulsed signal to data bits).

You will need a different part like:

http://www.fairchildsemi.com/ds/QS/QSC112.pdf

Fish
 
  • #7


thankyou...

if the link will not work (but the ckt is one whch came on e4u magazine!) i'll be glad if you could refer some similar circuit..
 
  • #8


If it looks like a LED, then it might be OK. Remote control receivers usually look like the picture above, that is fairly flat with a window on one side.

Try testing it as a transistor but with the top of the device covered over to stop light getting in.
A digital multimeter will usually be able to test transistors in the Hfe setting.

If it tests OK as a transistor, disconnect the base connection and expose the device to light and see if you get a variation in meter reading.


if the link will not work (but the ckt is one whch came on e4u magazine!) i'll be glad if you could refer some similar circuit..

"the link will not work" means that if we click on the link we get no picture, not that the circuit in the link won't work.
 
  • #9


27608d1237915931-infrared-cordless-headphone-ir_audio2.gif


this is the reciever circuit.
and here is the transmitter
27303d1237138691-infrared-cordless-headphone-ir_audio1.gif
 
  • #10


diegovishnu said:
27608d1237915931-infrared-cordless-headphone-ir_audio2.gif


this is the reciever circuit.
and here is the transmitter
27303d1237138691-infrared-cordless-headphone-ir_audio1.gif

In the transmitter circuit, T1 base appears to fed with a relatively large audio signal without any added DC bias. I believe that this is likely to give a grossly distorted result - are you certain that this has been drawn correctly?
 

1. What is a circuit?

A circuit is a closed path through which electricity can flow. It is made up of various components such as wires, resistors, capacitors, and batteries that work together to allow electricity to flow and power devices.

2. Why is it important to understand circuits?

Understanding circuits is important because they are the building blocks of all electronic devices. By understanding how circuits work, we can design and build more complex electronic systems to meet our needs.

3. What are the basic components of a circuit?

The basic components of a circuit include a power source (such as a battery), conductors (such as wires), and components (such as resistors, capacitors, and diodes). These components work together to control the flow of electricity.

4. How do you build a circuit?

To build a circuit, you will need a power source, conductors, and components. First, connect the positive terminal of the power source to one end of the conductor, and the negative terminal to the other end. Then, add components to the circuit by connecting them to the conductors. Finally, complete the circuit by connecting the remaining end of the component to the negative terminal of the power source.

5. What are some common problems when working with circuits?

Some common problems when working with circuits include short circuits, open circuits, and incorrect connections. These can cause the circuit to not work properly or even damage the components. It is important to carefully follow circuit diagrams and double check all connections to avoid these issues.

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