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DTMF Display kit

DTMF Opto Decoder kit with Relay output

DTMF Keypad Encoder kit

DTMF Detector kit

Our DTMF decoder kit has 6 NPN open collector Darlington outputs that can be switched on/off remotely with or without a 4 digit security code. The decoder also has a TX keying output to key a transmitter for transponding a Morse confirmation. An audio output is included for the Morse audio tones. The PCB has been designed to allow 3 input configurations - unbalanced audio, an Electret microphone or balance audio to be connected.

An alternative option is to use the kit as a DTMF to PC interface allowing DTMF tones to be displayed in say HyperTerminal (see below).

To turn on/off an output send the decoder its ID followed by the output number and * for ON or # for OFF e.g. 12341* turns on output 1 and 12342# turns off output 2 etc.

To toggle an output send e.g. 12341A and the state of the output will be changed to the opposite of its previous state - the Morse transpond will be confirmation of the new state. To pulse an output send e.g. 12341B and the output will turn on for 0.5 seconds - the Morse transpond will be e.g. 1P.

* You can now use 9 for A and 8 for B on the latest firmware.

For confirmation of the desired switching of an output the decoder will key a Transmitter and respond in Morse code, e.g. turning on output 1 will respond as 1 ON in Morse, and turning off output 2 will respond as 2 OFF.  As there are only 6 digits and 3 letters to learn, Morse shouldn't put you off.  There is a 2 second transpond delay followed by a 400ms link establishment delay to allow for CTCSS (if used).

Sending the turn off code for the dummy output zero e.g. 12340# will transpond _._._ OFF but won't affect any outputs. This is useful for checking if in radio range.

The 4 digit security ID can be changed by simply fitting a jumper to CN7, powering up the decoder and sending it a new 4 digit ID with DTMF, then remove power, remove jumper and power-up and the new ID is set.  If no ID is required then simply program the ID as 0000 and on next power-up no ID will be needed and e.g. 1* will turn on output 1.

There is an added feature on the current DTMF decoder kits, the ability to turn off the Morse transpond has been added.  When setting the 4 digit identity add a fifth digit as 9 and the Morse transpond will be turned off.  Any other character in the fifth position turns the morse transpond on. When supplied the identity is supplied as 1234 and the fifth digit is set as 0. You do not need to program the fifth digit if transpond is desired, the fifth digit is not used as part of the identity.

The PCB alone can be order from the components page.

All parts shown in the assembled photo are included as well as some extras for alternative input configuration.

Click here for pdf document with all the details

Click here for HT9170 datasheet

Click here for Amateur Radio TNC connector to DTMF wiring info

If using the kit for DTMF to serial - program the ID as 2320 and on next power-up decoded DTMF tones will be output as RS232 (4800 baud 8N1) compatible serial on the TX keying output, (fit the pull-up resistor R12 for this use).

The PCB is a high quality double sided PTH (plated through hole) 1.6mm FR4 (Fiberglass) board 64 x 38mm in size.

A 4 pin programming header is also provided to allow in-circuit re-programming of the PIC.
 

As an example if using as a DTMF code lock, use a mobile phone's keypad tones and use the microphone option for pick up.

Our DTMF Opto decoder kit has one relay output offering clean contacts, and one Opto coupled input offering complete isolation from the circuit being monitored.

The output can be switched on/off remotely with or without a 4 digit security code. The decoder also has a TX keying output to key a transmitter for transponding a Morse confirmation. An audio output is included for the Morse audio tones. The PCB has been designed to allow 3 input configurations - unbalanced audio, an Electret microphone or balance audio to be connected.

The Opto input can be interrogated and a Morse confirmation received confirming the current state (on or off).

To turn the Output on/off send the decoder its ID followed by 0 and * for ON or # for OFF e.g. 12340* turns the output on and 12340# turns the output off.

You can use 9 for A and 8 for B with 12 key DTMF pad.

For confirmation of the switching of the output the decoder will key a Transmitter and respond in Morse code. Turning on the output will respond as 0 ON in Morse, and turning off the output will respond as 0 OFF. There is a 2 second transpond delay followed by a 400ms link establishment delay to allow for CTCSS (if used).

To interrogate the current state of the Opto 1nput send the ID followed by 1* e.g. 12341* and the decoder will transpond in Morse 1 OFF or 1 ON depending on the input state.

To interrogate the state of the output without changing it send the ID followed by 2* e.g. 12342*

The 4 digit security ID can be changed by simply fitting a jumper to the middle 2 pins of CN3, powering up the decoder and sending it a new 4 digit ID with DTMF, then remove power, remove jumper and power-up and the new ID is set. If no ID is required then simply program the ID as 0000 and on next power-up no ID will be needed and e.g. 0* will turn on the output.

The PCB alone can be order from the components page.

All parts shown in the assembled photo are included as well as some extras for alternative input configuration.

Click here for pdf document with all the details.

Click here for HT9170 datasheet

Click here for Amateur Radio TNC connector to DTMF wiring info

The PCB is a high quality Gold Plated double sided PTH (plated through hole) 1.6mm FR4 (Fibreglass) board 64 x 38mm in size.

CN3 can also be used for in-circuit re-programming of the PIC with your own code.

There are many sources of DTMF, tone pads, two-way radio microphone keypads, telephone systems, and even your mobile phone's keypad tones.

As an example if using as a DTMF code lock, use a mobile phone's keypad tones and use the microphone option for pick up.

Our DTMF display can display up to 16 characters (8 per line). The display can be cleared by a button (not supplied) or can auto clear on a timed basis from receipt of the last character.

The input circuit is the same as the DTMF decoder kit above, therefore it can be configured for unbalanced, balanced or microphone input.  When an electret microphone is connected it can pick-up tones from a speaker phone a few inches away.

Connecting a momentary on button between the button input pin and 0V pin clears the display on pressing, however holding the button during power-up enables the timed reset mode. In timed reset mode the display is automatically cleared 10 seconds after the last character is received.

Complete kit of parts including pre-programmed PIC micro, gold plated PCB, LCD display, nuts bolts and spacers.

Runs from 7 to 16V DC at a few mA.

This kit is supplied with a backlit display, the backlight requires 4.05V at up to 60mA (e.g. 13.8V via a 220 ohm ½ watt resistor). The backlight is not connected in any way to the decoder PCB.

The PCB alone can be order from the components page.

Click here for HT9170 datasheet

Click here for Amateur Radio TNC connector to DTMF wiring info

Our DTMF encoder can encode all 16 DTMF tone pairs directly from a keypad as well as 8 single tones.

Tones are generated for as long as a key is pressed, and the tone audio output from the HT9200 encoder IC is amplified, buffered and filtered before the output level control, improving the overall quality of the generated signal.

A transmit keying open collector output (active low) is provided which activates on first key press, an inter-digit holding time of 1 or 1.5 seconds is included to keep the transmitter on between key presses. Fit the jumper to CN4 to reduce the delay to 1 second, otherwise 1.5 seconds is used.

There is also the option of grounding the function input (see circuit), the encoder then encodes the 8 tones used in DTMF as single tones when pressing buttons 1 to 8. This is useful for checking the frequency response of connected audio paths or transmitters/receivers etc.

Complete kit of parts including pre-programmed PIC micro and gold plated PCB.

The keypad is optional as this kit will work with most matrix keypads, the order of pin out varies between keypads and this should be checked if using a different keypad. The keypad can be connected via wires if desired, often necessary with other keypads.

The PCB has been designed with pads on the back for 1nF 0805 ceramic capacitors for RF decoupling on all inputs and outputs if needed, these are not supplied and not expected to be needed except in high level RF environments.

Runs from 7 to 16V DC at a few mA.

The PCB alone can be order from the components page.

Our DTMF detector kit allows the quick implementation of the HT9170 DTMF receiver IC.

Three input configurations are possible, un-balanced audio, balanced audio and microphone.

The 4 binary outputs of the HT9170 together with the data valid (DV) strobe are made available on the 8 pin connector; together with the output enable input (OE) and the power connections.

If output enable is not required just link it to the 5V pin. The kit will work on 3V to 5V DC therefore the kit can also be used with say 3.3V logic.

The PCB is double sided PTH (plated through hole), 38mm x 30.5mm in size and Gold Plated.

All parts shown in the assembled photo are included as well as some extra resistors (2 x 10K) for alternative input configuration.

The pins can be fitted on the top or on the back of the PCB. Fitting the pins on the back allows fitting the whole assembly onto 0.1” pitch boards.
 

The PCB alone can be order from the components page.

Click here for HT9170 datasheet

Click here for Amateur Radio TNC connector to DTMF wiring info

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