I'm being asked to make some replacement FSK modems for a system I designed about 30 years ago... not much money to be made, really just a charity job. I originally used the XR2206 as the transmit oscillator, and they are gone. Well, Mouser has one piece for $83. MAX038 is gone, too. Jameco has some 2206 DIPs, which I could scoop up, I guess. Anybody know of a classic analog sinewave generator chip? A uP and DDS would be a lot of hassle. And I'd like to be able to set the mark/space frequencies with pots. I guess I could make a triangle oscillator and sort of bend it into a sine wave. THD wouldn't matter much. The receive direction is easy. I'll use my almost-famous dual tach circuit https://dl.dropbox.com/u/53724080/Circuits/DoubleTach.jpg with a decent output filter and a comparator. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
are all the function generators gone?
Started by ●December 12, 2012
Reply by ●December 12, 20122012-12-12
On Wed, 12 Dec 2012 14:51:48 -0800, John Larkin wrote:> I'm being asked to make some replacement FSK modems for a system I > designed about 30 years ago... not much money to be made, really just a > charity job. I originally used the XR2206 as the transmit oscillator, > and they are gone. Well, Mouser has one piece for $83. MAX038 is gone, > too. Jameco has some 2206 DIPs, which I could scoop up, I guess. > > Anybody know of a classic analog sinewave generator chip? A uP and DDS > would be a lot of hassle. And I'd like to be able to set the mark/space > frequencies with pots. > > I guess I could make a triangle oscillator and sort of bend it into a > sine wave. THD wouldn't matter much. > > The receive direction is easy. I'll use my almost-famous dual tach > circuit > > https://dl.dropbox.com/u/53724080/Circuits/DoubleTach.jpg > > with a decent output filter and a comparator.At audio frequencies? Why waste time, board space, money, and power dissipation on a DDS when even cheap-ass 8-bit processors come in 40MHz models? Generate your sine wave on a PWM pin, filter it, and be happy. If you want to set mark and space frequencies with pots -- fine: cheap-ass 8-bit processors come with ADCs, that can be done. If the notion of using PWM to generate a "clean" signal makes you itch (XR2206? Clean?), then use a DAC. You'll spend less time writing the software than you will trying to source the chips you want. Then either use an ADC on-chip and implement your famous dual-tach signal processing in software, or just lick the back of that schematic and put it onto your board (since this is a charity job). -- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
Reply by ●December 12, 20122012-12-12
On Dec 12, 5:51=A0pm, John Larkin <jlar...@highlandtechnology.com> wrote:> I'm being asked to make some replacement FSK modems for a system I > designed about 30 years ago... not much money to be made, really just > a charity job. I originally used the XR2206 as the transmit > oscillator, and they are gone. Well, Mouser has one piece for $83.> MAX038 is gone, too. Jameco has some 2206 DIPs, which I could scoop > up, I guess.Do you need a lot? We've got several tubes left over from a discontinued gizmo*.> > Anybody know of a classic analog sinewave generator chip? A uP and DDS > would be a lot of hassle. And I'd like to be able to set the > mark/space frequencies with pots. > > I guess I could make a triangle oscillator and sort of bend it into a > sine wave. THD wouldn't matter much.You could use a clocked 4017 with different R's into a opamp summing junction. (Phil or James suggested it a while back.) With ten steps you move most of the 'distortion' out to the 9th and 11th harmonic. George H. *Teachscope, sold for a few hundred and put out 12 different 'signals' that the students would have to 'go find' with a 'scope. I wish someone would make the current day equivalent out of a uC.> > The receive direction is easy. I'll use my almost-famous dual tach > circuit > > https://dl.dropbox.com/u/53724080/Circuits/DoubleTach.jpg > > with a decent output filter and a comparator. > > -- > > John Larkin =A0 =A0 =A0 =A0 Highland Technology, Inc > > jlarkin at highlandtechnology dot comhttp://www.highlandtechnology.com > > Precision electronic instrumentation > Picosecond-resolution Digital Delay and Pulse generators > Custom laser drivers and controllers > Photonics and fiberoptic TTL data links > VME thermocouple, LVDT, synchro =A0 acquisition and simulation
Reply by ●December 12, 20122012-12-12
On Dec 12, 11:51=A0pm, John Larkin <jlar...@highlandtechnology.com> wrote:> I'm being asked to make some replacement FSK modems for a system I > designed about 30 years ago... not much money to be made, really just > a charity job. I originally used the XR2206 as the transmit > oscillator, and they are gone. Well, Mouser has one piece for $83. > MAX038 is gone, too. Jameco has some 2206 DIPs, which I could scoop > up, I guess. > > Anybody know of a classic analog sinewave generator chip? A uP and DDS > would be a lot of hassle. And I'd like to be able to set the > mark/space frequencies with pots. > > I guess I could make a triangle oscillator and sort of bend it into a > sine wave. THD wouldn't matter much. > > The receive direction is easy. I'll use my almost-famous dual tach > circuit > > https://dl.dropbox.com/u/53724080/Circuits/DoubleTach.jpg > > with a decent output filter and a comparator. >what frequencies? -Lasse
Reply by ●December 12, 20122012-12-12
George Herold wrote:> > *Teachscope, sold for a few hundred and put out 12 different 'signals' > that the students would have to 'go find' with a 'scope. I wish > someone would make the current day equivalent out of a uC.Have you ever tried a cheap DDS? Here is a module with an AD 8950 for under $8. It can be driven by a small processor, and Analog Devices has a demo program with a simple parallel port interface to play with. They offer sample code for the 8051, (I think. It's been a while since I looked) http://www.ebay.com/itm/280840956721 which is 0 to 40 MHz, and can have the outrput level set by software.
Reply by ●December 12, 20122012-12-12
On Wed, 12 Dec 2012 15:27:55 -0800 (PST), "langwadt@fonz.dk" <langwadt@fonz.dk> wrote:>On Dec 12, 11:51�pm, John Larkin <jlar...@highlandtechnology.com> >wrote: >> I'm being asked to make some replacement FSK modems for a system I >> designed about 30 years ago... not much money to be made, really just >> a charity job. I originally used the XR2206 as the transmit >> oscillator, and they are gone. Well, Mouser has one piece for $83. >> MAX038 is gone, too. Jameco has some 2206 DIPs, which I could scoop >> up, I guess. >> >> Anybody know of a classic analog sinewave generator chip? A uP and DDS >> would be a lot of hassle. And I'd like to be able to set the >> mark/space frequencies with pots. >> >> I guess I could make a triangle oscillator and sort of bend it into a >> sine wave. THD wouldn't matter much. >> >> The receive direction is easy. I'll use my almost-famous dual tach >> circuit >> >> https://dl.dropbox.com/u/53724080/Circuits/DoubleTach.jpg >> >> with a decent output filter and a comparator. >> > >what frequencies? > >-LasseClose to Bell 202 (1200/2200 Hz) but not so close that DSP-based 202 chips will work. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Reply by ●December 12, 20122012-12-12
John Larkin wrote:> > I'm being asked to make some replacement FSK modems for a system I > designed about 30 years ago... not much money to be made, really just > a charity job. I originally used the XR2206 as the transmit > oscillator, and they are gone. Well, Mouser has one piece for $83. > MAX038 is gone, too. Jameco has some 2206 DIPs, which I could scoop > up, I guess. > > Anybody know of a classic analog sinewave generator chip? A uP and DDS > would be a lot of hassle. And I'd like to be able to set the > mark/space frequencies with pots. > > I guess I could make a triangle oscillator and sort of bend it into a > sine wave. THD wouldn't matter much. > > The receive direction is easy. I'll use my almost-famous dual tach > circuit > > https://dl.dropbox.com/u/53724080/Circuits/DoubleTach.jpg > > with a decent output filter and a comparator.Here are 100 for $276.00: <http://www.ebay.com/itm/100-XR-2206-XR2206-XR2206CP-DIP-IC-NEW-m-/390442466659?pt=LH_DefaultDomain_0&hash=item5ae82f3d63>
Reply by ●December 12, 20122012-12-12
On Wed, 12 Dec 2012 15:14:48 -0800 (PST), George Herold <gherold@teachspin.com> wrote:>On Dec 12, 5:51�pm, John Larkin <jlar...@highlandtechnology.com> >wrote: >> I'm being asked to make some replacement FSK modems for a system I >> designed about 30 years ago... not much money to be made, really just >> a charity job. I originally used the XR2206 as the transmit >> oscillator, and they are gone. Well, Mouser has one piece for $83. > > >> MAX038 is gone, too. Jameco has some 2206 DIPs, which I could scoop >> up, I guess. > >Do you need a lot? We've got several tubes left over from a >discontinued >gizmo*. > >> >> Anybody know of a classic analog sinewave generator chip? A uP and DDS >> would be a lot of hassle. And I'd like to be able to set the >> mark/space frequencies with pots. >> >> I guess I could make a triangle oscillator and sort of bend it into a >> sine wave. THD wouldn't matter much. > >You could use a clocked 4017 with different R's into a opamp summing >junction. (Phil or James suggested it a while back.) With ten steps >you move most of the 'distortion' out to the 9th and 11th harmonic. > >George H. > >*Teachscope, sold for a few hundred and put out 12 different 'signals' >that the students would have to 'go find' with a 'scope. I wish >someone would make the current day equivalent out of a uC. > >> >> The receive direction is easy. I'll use my almost-famous dual tach >> circuit >> >> https://dl.dropbox.com/u/53724080/Circuits/DoubleTach.jpg >> >> with a decent output filter and a comparator. >> >> -- >> >> John Larkin � � � � Highland Technology, Inc >> >> jlarkin at highlandtechnology dot comhttp://www.highlandtechnology.com >>[snip non-compliant sig] You can easily make a modem from active filter structures. That's what I used for the OmniComp/GenRad international-frequency-selectable modem circa 1981-82... dirt cheap but very accurate. The discriminator was patented... http://www.analog-innovations.com/SED/Pat-4472816.pdf Much better performance in the presence of noise than the TI digital chips of that era. (I'll have to dig thru my lab notes, but I may even have used an LM324 :-) I'm trying to remember now, but I most likely used something like this for the transmitter... http://www.analog-innovations.com/SED/Sedra-Espinosa-Oscillator.pdf ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Reply by ●December 12, 20122012-12-12
On Dec 13, 12:58=A0am, John Larkin <jlar...@highlandtechnology.com> wrote:> On Wed, 12 Dec 2012 15:27:55 -0800 (PST), "langw...@fonz.dk" > > > > > > > > > > <langw...@fonz.dk> wrote: > >On Dec 12, 11:51 pm, John Larkin <jlar...@highlandtechnology.com> > >wrote: > >> I'm being asked to make some replacement FSK modems for a system I > >> designed about 30 years ago... not much money to be made, really just > >> a charity job. I originally used the XR2206 as the transmit > >> oscillator, and they are gone. Well, Mouser has one piece for $83. > >> MAX038 is gone, too. Jameco has some 2206 DIPs, which I could scoop > >> up, I guess. > > >> Anybody know of a classic analog sinewave generator chip? A uP and DDS > >> would be a lot of hassle. And I'd like to be able to set the > >> mark/space frequencies with pots. > > >> I guess I could make a triangle oscillator and sort of bend it into a > >> sine wave. THD wouldn't matter much. > > >> The receive direction is easy. I'll use my almost-famous dual tach > >> circuit > > >>https://dl.dropbox.com/u/53724080/Circuits/DoubleTach.jpg > > >> with a decent output filter and a comparator. > > >what frequencies? > > >-Lasse > > Close to Bell 202 (1200/2200 Hz) but not so close that DSP-based 202 > chips will work. >hard to beat a <50cent mcu at those frequencies -Lasse
Reply by ●December 12, 20122012-12-12
John Larkin <jlarkin@highlandtechnology.com> wrote:> >I'm being asked to make some replacement FSK modems for a system I >designed about 30 years ago... not much money to be made, really just >a charity job. I originally used the XR2206 as the transmit >oscillator, and they are gone. Well, Mouser has one piece for $83. >MAX038 is gone, too. Jameco has some 2206 DIPs, which I could scoop >up, I guess. > >Anybody know of a classic analog sinewave generator chip? A uP and DDS >would be a lot of hassle. And I'd like to be able to set the >mark/space frequencies with pots.You could hook the pots to the A/D inputs of a controller :-) Otherwise use an NE555-ish chip and filter the output... -- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico@nctdevpuntnl (punt=.) --------------------------------------------------------------
