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Old 18th Nov 2020, 7:25 pm   #1
Mikey405
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Default Chinese Pulse to DTMF Converters

Hi all.

I wonder whether anyone has had any experience of the cheap(ish) Chinese pulse-to-DTMF converters on eBay such as the one in the photo. I ordered one but it seems not to work terribly well. I've tried it on my 746 and 741 phones and in both cases it never dials the correct numbers. The DTMF tones are quite clearly (and loudly) heard in the earpiece - which is quite off-putting but excusable I guess, but I'm not 100% sure it's detecting the number of pulses correctly, and so dialling the wrong number. Some of the tones don't sound quite right to me either.

Also the arrangement of plug and socket is, to my way of thinking, a strange way to do things. The connection which goes to to the wall socket is also a socket (RJ11) - although RJ11 to RJ11 leads are easily available - and the end which connects to the phone is a pair of screw terminals (to which you can connect another socket on a trailing wire if you so wish).

I guess I should have paid the extra 25 pounds (including postage) and bought a Dialgizmo from Australia - but I thought I'd give one of these a try. Possibly a false economy...

Anyway, if anyone has had any experiences regarding these devices then I'd be most interested to hear.

Thanks all.

Kind regards.

From Mike.
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Old 18th Nov 2020, 8:05 pm   #2
Dave Moll
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Default Re: Chinese Pulse to DTMF Converters

I've not tried that one - though I had come across it. Yes, the arrangement of a socket for the line and screw terminals for the 'phone is a bit odd.

I trust that it is successfully suppressing the loop-disconnect pulses from the output, otherwise a line that accepts either will be receiving extraneous digits.

My favourite is the Dialgizmo. I've not had any problems with it misconverting. The only problem I found was that, for some reason, it woudn't work with my Silicon Arrays telephone tester, though it works fine on an actual telephone line.

Given that I have a Rotatone, a stand-alone converter from Oldphoneworks and a Dialgizmo, perhaps I ought to complete the set with one of these.
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Old 18th Nov 2020, 8:32 pm   #3
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Default Re: Chinese Pulse to DTMF Converters

Quote:
Originally Posted by Mikey405 View Post
Hi all.

I wonder whether anyone has had any experience of the cheap(ish) Chinese pulse-to-DTMF converters on eBay such as the one in the photo. I ordered one but it seems not to work terribly well. I've tried it on my 746 and 741 phones and in both cases it never dials the correct numbers. The DTMF tones are quite clearly (and loudly) heard in the earpiece - which is quite off-putting but excusable I guess, but I'm not 100% sure it's detecting the number of pulses correctly, and so dialling the wrong number. Some of the tones don't sound quite right to me either.

Also the arrangement of plug and socket is, to my way of thinking, a strange way to do things. The connection which goes to to the wall socket is also a socket (RJ11) - although RJ11 to RJ11 leads are easily available - and the end which connects to the phone is a pair of screw terminals (to which you can connect another socket on a trailing wire if you so wish).

I guess I should have paid the extra 25 pounds (including postage) and bought a Dialgizmo from Australia - but I thought I'd give one of these a try. Possibly a false economy...

Anyway, if anyone has had any experiences regarding these devices then I'd be most interested to hear.

Thanks all.

Kind regards.

From Mike.
Only 6 more - US$39.85 which equals 30.08 including postage. . I've had no problem with the Dialgizmo's plus they have ability to use a 'reverse' New Zealand dial!
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Old 18th Nov 2020, 9:12 pm   #4
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Default Re: Chinese Pulse to DTMF Converters

A further thought is how fussy this unit is about pulse speed and the mark to space ratio. If you have a 'phone that generates LD pulses electronically, it would be worth trying that, as these generate more reliable pulses than a mechanical dial.
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Old 19th Nov 2020, 10:43 am   #5
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Default Re: Chinese Pulse to DTMF Converters

I have tested several, but not that one. 1 of 5 dialgizmo'e has not worked stable, still those 4 others are so well working that I recommend them. Also here you will hear the dtmf after each digit. I have bought 3 of these:https://www.aliexpress.com/item/4000...archweb201603_ who is related to the one you are asking about. One of them stopped working after a few weeks, the last one has not been tested for real yet, so again Dialgizmo is a reasonable good solution.

Still the very best so far is the Smart-1 from Mitel, big, heavy and difficult to set up, but when it works you will not hear or notice that it is there in the system.

dsk

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Old 19th Nov 2020, 11:48 am   #6
Dave Moll
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Default Re: Chinese Pulse to DTMF Converters

At that price (12.30 including postage) I might risk trying one - and if I order it today, it looks as though it will be delivered by Santa Claus, given that no one else is likely to be delivering that day!
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Old 19th Nov 2020, 3:53 pm   #7
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Default Re: Chinese Pulse to DTMF Converters

I don't know if one is better than the other, but that one is different to Mike's picture, it has two chips, in fact I can't find a listing showing a board like Mike's with one chip.
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Old 19th Nov 2020, 4:24 pm   #8
Dave Moll
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Default Re: Chinese Pulse to DTMF Converters

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I can't find a listing showing a board like Mike's with one chip.
If you search eBay for "pulse dtmf", you should see a few that look like Mike's.
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Old 19th Nov 2020, 4:56 pm   #9
ThePillenwerfer
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Default Re: Chinese Pulse to DTMF Converters

From what I can tell the one Mike has bought works, or is supposed to, like DialGizmo whereas the ones DSK and Dave have linked to are like RotaTones.
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Old 19th Nov 2020, 5:38 pm   #10
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Default Re: Chinese Pulse to DTMF Converters

Hi Joe,
Speaking of Gizmo clones, I found this last night

http://www.mattmillman.com/projects/...one-converter/

Matt has simplified the Cherkasskiy-Weber hardware, and had also modified the code.

There is lots of interest in the comments section, but I suspect some will struggle programming the chip, without a step-by-step guide.
I left a comment attempting to address this, but it hasn't appeared, maybe he needs to moderate them first.
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Old 19th Nov 2020, 5:46 pm   #11
ThePillenwerfer
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Default Re: Chinese Pulse to DTMF Converters

I tried that briefly but had problems with noise. I may have done something wrong so should have another go at some point.

There's also an open-source Rotatone-type here: https://hackaday.io/project/28557-pu...tone-converter. I've never tried it as I haven't got the bits 'in stock' and am loathe to buy them given that I'd have to re-design the PCB for through-hole and that could well introduce errors reducing the chances of success.

I'm happy with what I've got.
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Old 19th Nov 2020, 6:29 pm   #12
winston_1
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Default Re: Chinese Pulse to DTMF Converters

I bought one of the Chinese ones like Mike. It didn't work and after a few emails got my money back.
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Old 19th Nov 2020, 6:50 pm   #13
Dave Moll
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Default Re: Chinese Pulse to DTMF Converters

Quote:
Originally Posted by ThePillenwerfer View Post
From what I can tell the one Mike has bought works, or is supposed to, like DialGizmo whereas the ones DSK and Dave have linked to are like RotaTones.
That would make sense that the Aliexpress one to which DSK linked is an internal rather than an external unit. Fortunately, I didn't rush to put it on my Santa list. I note, however, that Mike's one is also available from Aliexpress.
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