Reading Crystal Values

Hello I found some 2 pin crystal oscillators on various boards. However, I cannot figure out what values they are. I also do not have an oscilloscope.

They are marked, and these are their markings: R250CTB4F R160CTC4M R282CTB4A R0749000 R1430A16

My hunch is 25Mhz, 16Mhz, 7.49Mhz, 14.30Mhz. I may be wrong. Could someone shed some light?

Thanks!

Whats your guess on the R282CTB4A?

I tried a few google combinations, not seeing anything.

I found some 2 pin crystal oscillators

Not to nick pick, but I suspect what you have are some 2 pin crystal resonators. An oscillator would include a frequency determining resonator and a amplifier. In the standard arduino setup a crystal resonator is wired to the chip which contains an internal amplifier to form a crystal controlled oscillator. I bring this up because there are avalible external crystal oscillators that can come in a 4 pin package that have a ground, power, and TTL signal output pin that outputs a square wave at designed frequency.

Crystal resonator = : http://www.sparkfun.com/products/536

Crystal oscillator = : http://www.goldmine-elec-products.com/prodinfo.asp?number=G16490

A Atmel AVR controller chip can be setup to utilize either kind of device with proper fuse settings.

Lefty

Thanks retrolefty. I was wondering something along those lines. Sparkfun should rename that category to resonators...and they should add some 4 pin oscillators...so I can buy them... :)

The 4 pin oscillators are what I want for my external AM transmitter. Unfortunately I can't find any under 1.7Mhz. The old motherboard I have only has the 2 pin resonators that are of unknown frequency. I checked motherboards, soundcards, graphics card, wifi router, ethernet card, and even 7 old cellphones. The cellphones have the 4 pin SMD oscillators as well as resonators, but none in the desired frequency.

I tried 555 oscillation for AM radio and I thought it was too noisy and weak. I'm considering having the arduino feed input into the mic input of a walkie talkie...but I find that to be overkill and not as fun. :/

I have a broken radio controlled car. I'm going to try and reconfigure the radio circuit to send my own signals via arduino.

Jameco has four page of crystal oscillators:

http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDrillDownView?rf=1&history=r2v6cnju%7CfreeText%7Eoscillator%5Esearch_type%7Ejamecoall%5EprodPage%7E15%5Epage%7ESEARCH%252BNAV@6tlxrdl3%7Cposition%7E61%5Erf%7E1%5Erefine%7E1%5EprodPage%7E15%5Epage%7ESEARCH%252BNAV@tv1ihkn3%7Cposition%7E31%5Erf%7E1%5Erefine%7E1%5EprodPage%7E15%5Epage%7ESEARCH%252BNAV&position=1&refine=1&langId=-1&catalogId=10001&storeId=10001

A 1Mhz model would work in the AM band. And recall you can divide down any frequency by powers of two with simple logic flip-flops and counter chips.

Lefty

Thanks for the suggestion!

I ordered some stuff from digikey. Among them were two 1 Mhz crystal oscillators (4 pins).

Just to be safe. 1 Mhz, or 1000 Khz, is a legal band to broadcast on at under 100millivolts or less than 200ft reception right?

Also, how do frequency dividers work? I only recall flip-flops being used as railroad crossing signals...unless I'm missing the point.

Thanks!

Catcher: Thanks for the suggestion!

I ordered some stuff from digikey. Among them were two 1 Mhz crystal oscillators (4 pins).

Just to be safe. 1 Mhz, or 1000 Khz, is a legal band to broadcast on at under 100millivolts or less than 200ft reception right?

I believe that is still correct, however it's milliwatts not millivolts. There might also have been some antenna length and higth restrictions also.

Also, how do frequency dividers work? I only recall flip-flops being used as railroad crossing signals...unless I'm missing the point.

Pretty simple, with a type D flip-flop, if you wire the Q bar output to it's D input, and apply a digital clock frequency to the clock input, the Q output will be one half the input frequency. Binary counter chips are simply multiple flip-flops in a single package. So a 4 stage binary counter chip will have available the input frequency /2, /4, /8, /16 depending on which stage you take the output signal from.

Lefty Thanks!

Catcher is in MA, US rules will apply.

CrossRoads:
Catcher is in MA, US rules will apply.

MA?, hell that’s the home of bootleg broadcasting along, with it’s sister in heart, Berkeley, CA. All FCC rules are seem impotent there. There has been a guy living in a tree in Berkeley running a 20 watt FM band transmitter for years now. The Feds just seem to ignore him, probably because he doesn’t smell very good. :wink:

Lefty