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Glass-Giant

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  1. Could anyone give me thoughts on this used frequency counter (and it's price) that's available locally (no shipping charges)? I'm a total n00b with 3 different projects on the go (though stalled due to lack of time). 2 of the 3 could benefit from a frequency counter with this range. I don't have a frequency counter or oscilloscope yet. I've already asked for pics. Thanks, Shawn Fluke Counter Model 1950A 100/115/230 50-60 Hz Vac or 12Vdc power. With int/ext clock and gate BNC connectors. Ch A & B BNC inputs. Modes: Freq A, Freq(A/B)N, Period A, Totalize. 6 Ranges/Gate control. Overflow indicator. Cycle Rate control. A-input 5Hz-50MHz/ 1 Megohm. B-input 1KHz-10MHz/ 100Kohm. 2-LED trigger threshold indicator. 6-digits LED display... works completely. Dimensions: 9.3"W x 8.5"D x 3.6"H Calibrated about 3 years ago. Pics avaliable. Only $65.00
  2. I just realized I forgot to respond to the last 2 posts. Thanks, audioguru, for the clarification. That helps with my confidence in the transmitter (I wasn't sure if the transmitter or the receiver was the problem). And thanks for all your help codyhtml. If you don't get around to it, I think I can figure it out with your schematic and audioguru's picture.
  3. If I do find some money for a desktop, I've got a friend who builds them and gets his parts at wholesaler prices. So I'm good there. I'll have to see what I can get then for caps. I've been using ceramic. :-[ :-[
  4. And I'm an idiot. I knew that 72Hz - 41KHz range sounded wrong. I calculated again and it's actually 41KHz to 72KHz. Duh. So I added another resistor and a value of 9.18 Kohm should give me 38.1Khz. I think that should be plenty close enough to the ideal frequency. But I tried it and the receiver still isn't receiving. I'll likely still try the scope/decade counter thing to make sure the transmitter is okay. The digital camera indicated the led is firing. Thanks for the input everyone, Shawn
  5. That's a pretty good idea. I'll see if I can dig up the old set of instructions for a probe... It's so frustrating not knowing if my transmitter or receiver isn't working. I just calculated the frequency using the ACTUAL values of the resistors and capacitor, as measured by the DMM. The cap was pretty far off (0.65, instead of the 1nF I though it was). I think I read the code wrong. Anyway, the calculated frequency came out to be anywhere from 72Hz to 41KHz (with ~50% duty cycle), depending on the value of the pot (0-11.4KHz). I'm using a TSOP 1738 (38KHz) for testing the receiver. I'm assuming the 555 is reliable enough not to drift 3KHz. When I substitute a 1uF cap for the .65nF I can actually see the visible LED changing frequency as I turn the pot. It just dawned on me to use my digital camera to make sure the IR led is working. Back to the basement... I'm desperate for a new desktop, but can't justify the expense yet. :'(
  6. Um, the smiley seems to indicate a joke or a gloat. At the risk of sounding stupid, does it really have one like I would expect (a readout that says XXXKHz) or are you indicating that all you need to determine frequency is to know the resistance/capacitance values? Please explain to the dumb newb (using small words, if possible). :D
  7. The signal is from a 555, so I think that means it's square-wave. A good suggestion. I'll keep it in mind. From what I understand, the highest frequency which a sound card scope can identify is based on it's sampling rate. I've got 3 computers - 1 good laptop, 1 crappy PC and an old junked 233. I wouldn't risk the laptop on something I made myself (the probe). The crappy PC is, unfortunately, the main computer I use (I hate working on laptops), so ditto. I'm guessing the old 233's soundcard wouldn't go up to the 30-40KHz range, as CD-quality sound is 44Khz. I don't really know. But I guess I could use a sound card scope with the decade counter to give me much better results than by ear... It's kind of funny - this little project is going to lead to a bunch of other little projects (555 tester (done), bench power supply, parallel port pin status indicator (half done), sound card oscilloscope probe).
  8. I'm building an IR transmitter and receiver. I'm a newbie, working from untested plans, and am still making quite a few mistakes. The transmitter is based on a 555 in astable mode. I would like to make sure it works and is at least in the same order of magnitude as the desired frequency before making the receiver, but I don't have an oscilloscope. The transmitter works in the 30-60Khz range. So I can't verify it visually with a visible led substituted for the ir led. I was wondering if there would be a way to connect it to a speaker to generate a tone. As I understand it, the upper range of human hearing is about 20Khz, so I was wondering if there would be a way to only allow every 2nd or 3rd or 4th pulse through. I could then compare the tone to a known tone (assuming I can find a wav of the specific tone). Or maybe there's an easier way?
  9. I think your system and my planned one are orders of magnitude apart in terms of cutting power. ;) I guess I was making it more complicated than it needed to be.
  10. Out of curiosity, what's "stronger"? Mine are extremely wimpy. I have my fingers crossed that they will cut foam. I'll be ecstatic if they'll cut wood.
  11. Ah, I see now. I must have missed that on my first run through.
  12. Hi, Newbie here. I've been thinking of building a cnc mill for foam for a year or two now. I bought all the stuff for this board over the last year and stuff for a simple metal detector. Doing the metal detector now, as I've never made a pcb before. Will be starting the mill within the month. I must have missed this - where is ver 2.0? I didn't see it in the Projects section or in the previous comments. Or is ver 2.0 your own doing? Thanks, Shawn
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