| Electronics > Projects, Designs, and Technical Stuff |
| 3 Dollar Precision Frequency Standard |
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| Mechatrommer:
--- Quote from: Thor-Arne on April 10, 2015, 11:09:39 pm ---So no point in going for a as high at possible base frequency and divide it down. --- End quote --- there is, your tiny device will be capable of as high as possible frequency output. there is no pll output on that avr so you cant, say 1MHz base freq to produce multiplied 20MHz. i guess the fw is just adjusting its clk prescalers by button push. to push the limit further down, you can add dummy nops in your "led blinker" loop. and btw, the $3 avr is outputting square wave right? not pure sine? |
| Thor-Arne:
I took a quick search for oscillator used in the OP's pic, ebay retuned only one hit. Seller claims "I have no further specs available for this item as is is a proprietary part made by Raltron", so no datasheet I assume. It's $4.99 for a lot 5 units, shipping to Noway is $29.34. Which is not going to happen. :-- Shipping rates inside US should be acceptable. |
| paulie:
Yeah... that's just one of the dozen or so deals I snagged since getting into this last week. It does take some shopping effort. Like favorite fishing hole, few will beat a path to your doorstep to clue you in on best bargains. Generally to get good deals it may be necessary to buy more than one at a time and often takes some bidding or BO. Otherwise be prepared to spend a few dollars more. Getting "pretty" numbers cheap is a little harder but if you just need stabilty and accuracy like for calibrating scope or counter then absolute frequency don't matter. With a little luck and open eyes sometimes high performance devices that might cost $10 or $20 over the counter can be had for pennies: If you don't want to bother hunting for bargains then they are almost always available for a buck or two more: http://www.ebay.com/itm/181032108148?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT http://www.ebay.com/itm/191425644527?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT http://www.ebay.com/itm/160999666268?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT You can expect deals on Aliexpress to run a dollar or two below Ebay as a result of bandit Paypal fees. I rarely go that route myself though because of the excellent Ebay buyer protection. ps. Also note that temperature compensated is not the only option here. If your environment is relatively stable around room temperature a regular crystal with trim cap will often suffice. Two of my fellow amateur radio buffs went that route and very satisfied. In my case temperature in the shop varies too much. For example in the last week recorded from 6C to 22C. I only heat when working so TC is more than a luxury. YMMV |
| paulie:
--- Quote from: evb149 on April 11, 2015, 07:37:44 pm ---The comment about it running on an AAA cell made it seem like it was a PCB assembly product of some kind...? Most discrete oscillator through hole component units run on +5V or +3.3V or +2.5V or rarely +1.8V right? --- End quote --- Notice the photo and reference in OP to "USB DC-DC boost converter". These are available from china for 20-30 cents or sometimes for a buck at Dollar Tree like the one in my photo. In fact the oscillator in mine runs off anything from 3.3v-5v so a bare lithium AA technically requires no converter. However it is nice to be able to pop in a 1.2v NIxx or 1.5v alkaline in a pinch. Nothing says you have to use batteries anyway. 5v from a wall wart or USB plus works fine too. Personally I do like to be able to carry these projects around in my pocket and not depend on the "kindness of strangers" for power. BTW if you expect to get that kind of help on these forums it's a good idea to include at least country in your avatar. Child molesters unlikely to locate your home with such general info. |
| Vgkid:
If you start delving into part numbers, you can get some pretty schmick parts for not a lot of cash. |
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