How to connect DTMF decoder with telephone line?

Started by Ray2008 in sci.electronics.design9 years ago 6 replies

I want to use a DTMF decoder IC such as HT9170 to get the numbers. What confused me is how to connect the decoder with telephone line? Is the...

I want to use a DTMF decoder IC such as HT9170 to get the numbers. What confused me is how to connect the decoder with telephone line? Is the transformer necessary? Or can I have another solution? What=92s the means of the =93600-600 Ohm=94 marked with the transformer? Thank you very much! http://courses.cs.tamu.edu/rabi/past-projects/99a/g6/Image5.gif


differential Manchester decoder and FIFO

Started by p in sci.electronics.design4 years ago 28 replies

I need to make a bi-phase / differential Manchester decoder (max. frequency of recovered clock about 10MHz) and asynchronous FIFO 1 bit *...

I need to make a bi-phase / differential Manchester decoder (max. frequency of recovered clock about 10MHz) and asynchronous FIFO 1 bit * ~100...~1000. How can I do this and what is best suitable to do it ? Thanks in advance.


Tone decoder debug

Started by Ralph Olsen in sci.electronics.design6 years ago 6 replies

I have been trying to get this circuit to work all morning. The LED's are supposed to turn on when a 19.2KHz tone appears on the...

I have been trying to get this circuit to work all morning. The LED's are supposed to turn on when a 19.2KHz tone appears on the LM567's input. Here is the circuit. Originally downloaded off the net (identical from 2 sources) but I re-drew it in DipTrace to send here for clarity. Click the image to enlarge. http://www.4shared.com/photo/c5MHZYBD/Tone-decoder.html Any suggestions where ...


Binary to decimal decoder with open collector outputs?

Started by bitrex in sci.electronics.design2 years ago 8 replies

Did anyone make a 74** something or other that was a binary to one-of-ten decoder that had open collector/drain outputs that one could...

Did anyone make a 74** something or other that was a binary to one-of-ten decoder that had open collector/drain outputs that one could wired-OR together? I need to take a binary coded output from a logic IC that's in the 1 to 10 range and convert it to a single on/off decimal output in the range of 1 to 5. Maybe there's a better way to do this.


Referencing 42 bits

Started by mpm in sci.electronics.design3 years ago 24 replies

It's early AM here, no coffee in the house, so please forgive the following: :) I want to take 42 bits of information and encode, or condense...

It's early AM here, no coffee in the house, so please forgive the following: :) I want to take 42 bits of information and encode, or condense them, into a small string of text to that I can easily, and even verbally, communicate a whole bunch of information at once. The receiving end would have an appropriate decoder. Printable characters only. And ideally, restricted 0-9, A-Z


OT: Ceefax ends

Started by Martin Brown in sci.electronics.design5 years ago 7 replies

The original UK digital Ceefax channel transmitted as binary data in the hidden scan lines went off the air with the termination of all analogue...

The original UK digital Ceefax channel transmitted as binary data in the hidden scan lines went off the air with the termination of all analogue TV broadcasting in the UK this week. At one time it had an audience of over 20M but at initial launch there were just 4 decoder boxes in the entire country - all of them wire wrap prototypes. http://www.bbc.co.uk/news/uk-20032882 Though this...


Another question involving a monostable.

Started by Pimpom in sci.electronics.design5 years ago 28 replies

Scheme: I have these three different sources of irregular low-repetition-rate pulses, no two occurring at the same time, and I want to send...

Scheme: I have these three different sources of irregular low-repetition-rate pulses, no two occurring at the same time, and I want to send them over a long 2-core shielded cable. I suppose they could be sent as serial data, but my knowledge of MCUs is limited and dedicated encoder-decoder pair ICs introduce uncertainty periods of tens of milliseconds. Such periods can be tolerated but...


7-segment LCD to BCD decoder ?

Started by N_Cook in sci.electronics.design3 years ago 83 replies

Assuming one back-plane to consider , what would be most efficient component-count/least complex discrete/CMOS/74 route , ie not pic/Pi/uC to...

Assuming one back-plane to consider , what would be most efficient component-count/least complex discrete/CMOS/74 route , ie not pic/Pi/uC to firstly convert the ex-oring business to proper levels and then the "mapping", output could be linear per digit rather than bcd. Starting with an off-the-shelf commercial unit where the LCD display is driven off a uC, to give a remotely monitorable ...


Video grabber

Started by Grumps in sci.electronics.design8 years ago 51 replies

Hi I'm looking at making a video grabber that will grab VGA video with a pixel clock of up to 250MHz (approx). I've used monolithic decoders...

Hi I'm looking at making a video grabber that will grab VGA video with a pixel clock of up to 250MHz (approx). I've used monolithic decoders in the past which work fine. But the frequency does not go to 250MHz. Before I start evaluating what I need to do, is anyone aware of a suitable decoder that runs at this speed? Whether it's a monolithic part or even a complete board, I don't mind....


todays Ham Radio meeting..

Started by Jamie in sci.electronics.design6 years ago 8 replies

We had an auction at our ham radio meeting tonight of stuff that has been sitting around and thought maybe it was a good idea to liquidate...

We had an auction at our ham radio meeting tonight of stuff that has been sitting around and thought maybe it was a good idea to liquidate the un-needed items. I got for $1.00 a repeater remote control unit with DTFM decoder that handled 16 lines of control that I designed and built ~ 25 years ago now. This thing is still in operational shape even though it took some cosmetic r...


wave and rider

Started by Jon in sci.electronics.design5 years ago 8 replies

This is the signal I hope to create: https://sphotos-b.xx.fbcdn.net/hphotos-ash4/s480x480/2049_10151353534278810_133123559_n.jpg both the...

This is the signal I hope to create: https://sphotos-b.xx.fbcdn.net/hphotos-ash4/s480x480/2049_10151353534278810_133123559_n.jpg both the frequency of the blue wave and the frequency of the red rider wave are adjustable. I came up with the equation for the wave using vector calculus, but it is unlikely that the math decoder can crunch out a signal in real time at the press of a key....


encoder and decoder for compact representation of the prime numbers

Started by Jamie Morken in sci.electronics.design2 years ago 6 replies

Hi, The prime numbers can be stored with a density approaching 1 prime per bit by using a primorial set of equations. When the primes are...

Hi, The prime numbers can be stored with a density approaching 1 prime per bit by using a primorial set of equations. When the primes are compressed like this, any patterns in the distribution of the primes becomes apparent to see compared to the uncompressed primes in the natural numbers. Compression algorithms are related to pattern recognition so this maximally compact representation...


Universal Remote Control (proper one) / cracking coding?

Started by N_Cook in sci.electronics.design8 years ago 7 replies

2 vital functions only via missing remote control, not available to buy or borrow, to copy/learn from or to make a simple 2 function r/c. The...

2 vital functions only via missing remote control, not available to buy or borrow, to copy/learn from or to make a simple 2 function r/c. The other functions are setup menus that have no need to be on a remote. 7 data lines to 3x4 ,12 switch matrix on the unit and no odd spare lines. Large proprietory BGA controller does the decoding so totally hidden, no separate IR decoder available to moni...


How to Avoid Idle Signal on Ethernet Cable IEEE 802.3

Started by Klaus Kragelund in sci.electronics.design4 years ago 64 replies

Hi I have a system comprised of a computer with a TCP/IP application and a gateway connected to this computer. I need to measure the delay of...

Hi I have a system comprised of a computer with a TCP/IP application and a gateway connected to this computer. I need to measure the delay of the gateway, by measuring the delay on the output of the gateway and the signal on the ethernet line But, the ethernet line is active all the time and I do not have a TCP/IP decoder and it is impossible to trigger on the burried TCP/IP packet. From ...