youngqd@jacobs.cs.orst.edu (Dean Youngquist) (04/19/91)
I am making a small low power transmitter as an alarm system for my bicycle. It will have a small motion sensitive switch inside and will transmit when if the bike is moved. I would like to transmit audio picked up by a small mike, or at least I need to modulate the signal so I can hear it on my scanner. For space saving and cost reasons I would like to use one of those small can oscillators with 4 terminals. The only problem is how to modulate either the amplitude or the frequency of this device. I have noticed that varying supply voltage changes both the amplitude and frequency. Is this the best way? I don't have any spec sheets on these oscillators but I have determined V+, V-, and the output. The other pin seems to be no connection.
youngqd@jacobs.cs.orst.edu (Dean Youngquist) (04/20/91)
Message-I For space saving and cost reasons I would like to use one of those small can oscillators with 4 terminals. The only problem is how to modulate either the amplitude or the frequency of this device. I have noticed that varying supply voltage changes both the amplitude and frequency. Is this the best way? I don't have any spec sheets on these oscillators but I have determined V+, V-, and the output. The other pin seems to be no connection.
henry@zoo.toronto.edu (Henry Spencer) (04/21/91)
In article <1991Apr20.012710.266@ac.dal.ca> youngqd@jacobs.cs.orst.edu (Dean Youngquist) writes: > For space saving and cost reasons I would like to use one of > those small can oscillators with 4 terminals. The only > problem is how to modulate either the amplitude or the > frequency of this device... Very probably what you've got there is a crystal oscillator. There is basically *no way* to vary their amplitude or frequency very much. The frequency is fixed by the physical dimensions of the crystal, modulo small variations due to temperature and supply voltage, and the output (in the ones I'm familiar with) is from digital logic that only knows about 0 and 1, nothing in between. -- And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology "beans are more important". | henry@zoo.toronto.edu utzoo!henry
henry@zoo.toronto.edu (Henry Spencer) (04/21/91)
I wrote: >> For space saving and cost reasons I would like to use one of >> those small can oscillators with 4 terminals... >Very probably what you've got there is a crystal oscillator... My mistake; turns out there are other things that use the same package. -- And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology "beans are more important". | henry@zoo.toronto.edu utzoo!henry
smith@sndpit.enet.dec.com (Willie Smith) (04/22/91)
In article <1991Apr20.235945.7393@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes... >>> For space saving and cost reasons I would like to use one of >>> those small can oscillators with 4 terminals... >>Very probably what you've got there is a crystal oscillator... >My mistake; turns out there are other things that use the same package. Don't keep us in the dark Henry, what are those other things and how do they work? I've seen QRP plans that use 4-terminal oscillators, and I've always wondered why there was no filter indicated to get the square wave down to a sine wave.... Are there 4-terminal oscillators with (modulatable , is that a word?) sine-wave outputs? Willie Smith smith@sndpit.enet.dec.com smith%sndpit.enet.dec.com@decwrl.dec.com {Usenet!Backbone}!decwrl!sndpit.enet.dec.com!smith
youngqd@jacobs.CS.ORST.EDU (Dean Youngquist) (04/22/91)
For those who are interested I have been able to amplitude modulate the output from one of those 4 terminal crystal oscillators. I hooked the supply voltage in series with an ordinary telephone and then I could press the touch tone buttons or speak into the mike and this signal could be heard on a nearby reciever. My supply voltage across both xtal osc. and phone was 12 volts. The phone had 6.5 volts and the xtal osc had 5.5 volts. It seems like a new form of QRP has been born. Now, if I could just find some that allow me to tweek the frequency! Dean Youngquist youngqd@jacobs.cs.orst.edu 428 NW 9th St. Amateur Radio Operator N7LPE Corvallis, Oregon 97330 Tel. (503) 757-0335
kludge@grissom.larc.nasa.gov ( Scott Dorsey) (04/22/91)
In article <1991Apr20.235945.7393@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >I wrote: >>> For space saving and cost reasons I would like to use one of >>> those small can oscillators with 4 terminals... >>Very probably what you've got there is a crystal oscillator... > >My mistake; turns out there are other things that use the same package. Nope, he's probably using a crystal oscillator as you said (or one with a ceramic resonator). What he should be using is a voltage-controlled oscillator in a 4-pin can, like the ones that MuRata Erie make. I do heartily recommend them. --scott (or you can always open up the can and put a varactor diode across the element, then adjust the bias of the varactor to slew it like a VCXO)
koning@koning.enet.dec.com (Paul Koning) (04/30/91)
|>In article <1991Apr20.235945.7393@zoo.toronto.edu>, henry@zoo.toronto.edu (Henry Spencer) writes... |>>>> For space saving and cost reasons I would like to use one of |>>>> those small can oscillators with 4 terminals... |>>>Very probably what you've got there is a crystal oscillator... |>>My mistake; turns out there are other things that use the same package. |> |>Don't keep us in the dark Henry, what are those other things and how do |>they work? I've seen QRP plans that use 4-terminal oscillators, and I've |>always wondered why there was no filter indicated to get the square wave |>down to a sine wave.... Are there 4-terminal oscillators with (modulatable |>, is that a word?) sine-wave outputs? |> |>Willie Smith |>smith@sndpit.enet.dec.com |>smith%sndpit.enet.dec.com@decwrl.dec.com |>{Usenet!Backbone}!decwrl!sndpit.enet.dec.com!smith |> I'd certainly guess that this is a crystal oscillator. Keep in mind that they come in a vast number of variants. The majority is probably fixed frequency squarewave output, but you can also get them with sinewave output, and/or voltage controlled frequency (VCXO), etc. Squarewave output can be had in TTL levels (with either TTL or CMOS guts) or for higher frequencies you can get ECL levels. Lots of companies make these things; check your various catalogs or electronic component rags for pointers. paul, ni1d