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# telephone related question #2

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what is make/break ratio, and what these statements mean: "In normal mode
pin 10 (of UM9151) is used to select make/break ratio: when i/p = VDD, M/B =1/2
when i/p = VSS, M/B =2/3"

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Hi Walid,
The make/break ratio is the ratio of the time that rotary dial pulsing makes the phone's connection to the time it breaks the connection. Europe has a different standard than North America. Setting pin 10 either high or low selects the ratio, 50:50 or 67:33.

I don't know what is "normal mode", the datasheet should explain. Maybe the ratio is selectable only when the rotary dial pulses are 10pps (ten pulses per second), but remains as 50:50 for 20pps. ;D

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OK, this is a good answer, what I understood is when I dial number say 3 I hear teck - teck - teck -  which mean that telephone connect and disconnect three times that is M/B = (time of 1 teck) / (time of one -). Now the new question is if I live in USA and M/B ratio there is say 67:33 and I built a telephone device has a DTMF IC (say UM9102) and I connect pin 10 to VDD, that is choose a M/B ratio = 1/2 (not 67:33), is this telephone enable to call?
Secondly: is it true that M/B ratio takes place only in the pulse mode and
not in the tone mode?

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if I live in USA and M/B ratio there is say 67:33 and I built a telephone device has a DTMF IC (say UM9102) and I connect pin 10 to VDD, that is choose a M/B ratio = 1/2 (not 67:33), is this telephone enable to call?

Hi Walid,
I have made many telephone DTMF tone dialing projects, but I have never made one do rotary dial pulses. I don't remember what is the standard for M/B ratio in the USA and I don't know if it will work if it is incorrect.

Secondly: is it true that M/B ratio takes place only in the pulse mode and
not in the tone mode?

Yes, in tone mode there isn't a break. Sometimes tone mode has a programmable digit repetition rate. I used to program telephone systems that were on modern telco exchanges to dial 10 digits per second. Your IC can't dial tones that quickly. I laugh when I hear credit card machines dialing DTMF tones at only 2 digits per second. ;D
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From all of this discussion with Mr. audioguru about make/break ratio i conclude:
The make/break ratio is the ratio of the time that rotary dial pulsing makes the phone's connection to the time it breaks the connection. Europe has a different standard than North America. Setting M/B pin either high or low selects the ratio, 50:50 or 67:33. these ON - OFF (high - low or 1 - 0) swquence are given from some pin remarked as PO (out put pulse) or sometimes as DP (dialing pulse), when po (or dp) out 1 the telephone connect to line, where if po = 0 the telephone disconnected. For example if you press number 2, then PO (or DP) output sequence is 1010, and if you press number 4, then PO (or DP) output sequence is 10101010. You can do this maually (as audioguru tell me) by pressing and release the hook-switch by hand, for dialind number 3 press and release the hook-switch 3 time but you must do this acurately.
If M/B ratio = 50:50 this mean the on time = the off time, the only thing that i can not tell you about the value 50: 50 i guss 50 is the time period in mellisecond of ON or OFF.
thanks to audioguru.

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Hi Walid,
Good, now you understand how an electronic phone dials very well! ;D

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