Post by thread:FSK Modem

Hi all Has anyone made the fsk modem by Rildo Pragana? Im thinking of constructing it but am unclear on a few points. 1. C9, C11, C13, C14, C15 and R8's values are unclear. Does anyone know what they should be? 2. Transformer T1's size or value is unclear. 3. Will the modem work on Australian phone network? Can anyone fill in the blanks? Thanks Justin

part 0 454 bytes Hi all Has anyone made the fsk modem by Rildo Pragana? Im thinking of constructing it but am unclear on a few points. 1. C9, C11, C13, C14, C15 and R8's values are unclear. Does anyone know what they should be? 2. Transformer T1's size or value is unclear. 3. Will the modem work on Australian phone network? Can anyone fill in the blanks? Thanks Justin Attachment converted: wonderland:fskmodem.gif (GIFf/JVWR) (0000BE3C)

This Modem sounds interesting. It would be nice to get it working in South Africa as well. I did a quick search on the net for this modem and came up with this site http://www.qsl.net/~dg1scr/pr/epp/index_e.html, also interesting. Do you have a website where you got this .gif. Thanks > {Original Message removed}

I thought someone would like to see this: Circuit: http://www.ustr.net/modem/modem.gif Description: http://www.ustr.net/modem/modemdsc.htm Software (8051): http://www.ustr.net/modem/modem.asm I have few RC224ATF chips available if someone is interested.

I got the circuit from microchip net resources, I dont think he has a web page http://www.geocities.com/SiliconValley/Way/5807/ ----- Original Message ----- From: Russell Jonathan <spam_OUTRussellJTakeThisOuTFTG.CO.ZA> To: <.....PICLISTKILLspam@spam@MITVMA.MIT.EDU> Sent: Tuesday, 31 August 1999 20:38 Subject: Re: FSK Modem > This Modem sounds interesting. It would be nice to get it working in South > Africa as well. I did a quick search on the net for this modem and came up > with this site http://www.qsl.net/~dg1scr/pr/epp/index_e.html, also > interesting. > Do you have a website where you got this .gif. > Thanks > > > {Original Message removed}

Hello Justin, Sorry, I'm a bit late! Justin Grimm schrieb: > > Hi all > Has anyone made the fsk modem by Rildo Pragana? > Im thinking of constructing it but am unclear on a few points. > 1. > C9, C11, C13, C14, C15 and R8's values are unclear. Does > anyone know what they should be? A 10kpF means 10 * 1000 pF, 10nF. (If I'm not mistaken) and a 10k condensator should also have a value of 10nF. R8 has a value of 7500 Ohms (7.5 kOhms) > 2. > Transformer T1's size or value is unclear. It should be a 1:1 Transformer with 600 Ohms Inpedance. If you have an old phone left you can use its transformer. > 3. > Will the modem work on Australian phone network? > > Can anyone fill in the blanks? > Thanks > Justin I have not built it but it should work on almost every phone system... Friendly Regards Markus

Markus Rohe wrote: > It should be a 1:1 Transformer with 600 Ohms Inpedance. If you have an > old phone left you can use its transformer. I'd be *extremely* surprised if a telephone design in any country used a 1:1 transformer (which is the only actual specification. Transformers don't actually have impedance specifications in this regard). Most in fact use auto-transformers with quite odd ratios. Certainly no common phone in this country did. I think the above would more correctly read "If you have an old modem left you can use its transformer." Picky perhaps, but you'd be very disappointed searching for modem transformers in offcast telephones. Maybe in .DE ... -- Cheers, Paul B.

At 21:57 3/09/99 +0200, you wrote: {Quote hidden}>Hello Justin, > >Sorry, I'm a bit late! > >Justin Grimm schrieb: >> >> Hi all >> Has anyone made the fsk modem by Rildo Pragana? >> Im thinking of constructing it but am unclear on a few points. >> 1. >> C9, C11, C13, C14, C15 and R8's values are unclear. Does >> anyone know what they should be? > >A 10kpF means 10 * 1000 pF, 10nF. (If I'm not mistaken) and a 10k >condensator should also have a value of 10nF. R8 has a value of 7500 >Ohms (7.5 kOhms) > >> 2. >> Transformer T1's size or value is unclear. > >It should be a 1:1 Transformer with 600 Ohms Inpedance. If you have an >old phone left you can use its transformer. Do not use the transformer out of an old 800 series telephone, it is not 600R. Buy one off the shelf, the small size is not a problem as nor current should be flowing thorugh it. As for the line match, better look for a TN12 impedance (Complex) I don't suggest that you build this and connect it to a phone line Dennis {Quote hidden}> >> 3. >> Will the modem work on Australian phone network? >> >> Can anyone fill in the blanks? >> Thanks >> Justin > >I have not built it but it should work on almost every phone system... > >Friendly Regards >Markus > >