Ne567

[trennonix]

Hello,
What's the "bandwidth" in a NE567 chip? What does it define?

i want to build a RF receiver but i don't want to use any custom inductors for tuning; is there's a chip of some kind that can do the tuning for me using some variable resistor or capacitor for that? (freq range from 60 to 300 Mhz should do fine)

Thanks

 

[jahmad]

Hello,
this is jamil ,sorry to disturb u ,just tell me how i enter my own question into the tag
plz rep
thanks

 

[Nigel Goodwin]

Hello,
What's the "bandwidth" in a NE567 chip? What does it define?

i want to build a RF receiver but i don't want to use any custom inductors for tuning; is there's a chip of some kind that can do the tuning for me using some variable resistor or capacitor for that? (freq range from 60 to 300 Mhz should do fine)

You need inductors - an NE567 is also just an audio tone detector.

 

[trennonix]

i know what the ne567 is, i want to know what they meant by "bandwidth" in the datasheet
i'll be using the chip in a receiver; i'll be sending 2 tones, one is for zero bit and the other for high bit

 

[Nigel Goodwin]

i know what the ne567 is, i want to know what they meant by "bandwidth" in the datasheet
i'll be using the chip in a receiver; i'll be sending 2 tones, one is for zero bit and the other for high bit

The bandwidth is how near the tone has to be to the design frequency, so if the centre is 1KHz, then 1100Hz to 900Hz would be 200Hz bandwidth.

 

[trennonix]

ah, alright thanks alot

 

[marcbarker]

I know it's not directly answering OP... The 567 circuit's bandwidth increases with applied signal amplitude. It's also an 'audio' frequency device. They're not really good for recieving PCM data.

When using a 567, there's 3 capacitors: they set centRE frequency, bandwidth, and response time delay.

 

[trennonix]

So what do you suggest i use?

 

[marcbarker]

So what do you suggest i use?

For what?

 

[Nigel Goodwin]

So what do you suggest i use?

You want a tone detector, then use the NE567 - he never suggested there was any problem with using it.

 

[marcbarker]

i want to build a RF receiver but i don't want to use any custom inductors for tuning; is there's a chip of some kind that can do the tuning for me using some variable resistor or capacitor for that? (freq range from 60 to 300 Mhz should do fine)

Inductors are a simple and convenient way of tuning, and have been used for over a century in conjuction with capacitors. There is a huge range of off-the-shelf inductors available as an alternative to a custom design.

I have seen inductor-less 'tuning' circuits before at RF, using R-C circuits, but I have not so far seen an inductor-less tuned circuit above 60 MHz.

It will be interesting to see such an inductor-less tuned circuit operating above 60 MHz, or any chip that can be used in such. If anyone sees one please post it here.

 

[trennonix]

For what?

I don't know what PCM is, so out of the context of our discussion i thought that it was receiving coded ones and zeros

For my receiver, what do you suggest that i use as a signal amplifier?
would simple transistors do just fine or would i need an OP-AMP?

One more thing, RL circuit are used an oscillator in a transmitter, and the same RL circuit can be used for tuning, right?
So does this mean that i can use a crystal oscillator for tuning?

 

[Nigel Goodwin]

I don't know what PCM is, so out of the context of our discussion i thought that it was receiving coded ones and zeros

PCM is Pulse Code Modulation - I don't see why he mentioned it?, as you're presumably using ASK as you suggested earlier (post 4).

For my receiver, what do you suggest that i use as a signal amplifier?
would simple transistors do just fine or would i need an OP-AMP?

Either would do.

 

[trennonix]

thanks nigel, the post has been reedited before i had the chance to see your reply.
Hope you can answer my last question

 

[marcbarker]

PCM is Pulse Code Modulation - I don't see why he mentioned it?, as you're presumably using ASK as you suggested earlier (post 4).

PCM

#4 mentioned ASK, but 567's don't respond to ASK. I used the term 'PCM' loosely to make a distinction. The nearest a 567 will do is 'half' of ASK, that is detect the presence of a single tone only, which one it is a predetermined choice of the two. To detect both tones would require two 567's, one for each tone. The response time delay of the 567 makes it a poor choice for receiving data (which I loosely called 'PCM').

There's a multitude of ways of doing ASK demod., but 567s I would consider a poor choice, unless the data rate was about low i.e. 5 bps.

 

[trennonix]

yes i'm using 2 tones, but i only need one decoder since if the signal is not one, it's zero

Now the reason that i use 2 tones is that if i simply turn off the transmitter for zero, charged capacitors might keep sending the 'one' tone for some time reducing my baud rate.
I have no idea if the effect is great enough to have such a consequence, but it's a safety precaution for my lack in experience

Thus the need for 1 NE567

 

[marcbarker]

Thus the need for 1 NE567

And a data bit rate no faster than 5 bps. Maybe faster if the tone is higher Hz

 

[trennonix]

And a data bit rate no faster than 5 bps. Maybe faster if the tone is higher Hz

I've never said at which freq i was operating (if you're referring to '200Hz' that was the bandwidth not the frequency)
I was thinking of something around 1KHz; say 1KHz ON and 700Hz OFF
Would that be good for this chip to handle? and does this give me good bps?

 

[trennonix]

One more thing, RL circuit are used as an oscillator in a transmitter, and the same RL circuit can be used for tuning, right?
So does this mean that i can use a crystal oscillator for tuning?

 

[marcbarker]

I've never said at which freq i was operating (if you're referring to '200Hz' that was the bandwidth not the frequency)
I was thinking of something around 1KHz; say 1KHz ON and 700Hz OFF
Would that be good for this chip to handle? and does this give me good bps?

I see 'where you're coming from' now. You'll get about 2 bps with those frequencies!

Try something higher.