audioguru

Mixos, The highlighted part of my notify e-mail is also underlined. The part that is not highlighted is also not underlined, maybe that is the problem. It is difficult to copy and paste because my browser is not opened. Outlook Express opens my browser when I click on a highlighted URL. If I manually highlight the entire URL, then click on it, I still go to the index page. Many other web-forums work properly for me, why not this one?

Yevgenip, The formula for charging a capacitor through a resistor from a fixed voltage source is: R X C. Where R is in Ohms and C is in Farads. The result of the multiplication is in seconds, when the capacitor will have reached a voltage that is about 0. 63 of the fixed voltage. To calculate the time for it to charge to another voltage level, I refer to a graph in a book. For example, A 1M resistor charges a 10 microfarad capacitor in 10 seconds. The capacitor will almost reach its full charge (almost to the fixed voltage level) in a time that is 5 times as long. These calculations depend on having a measuring device or sensing circuit that has an input resistance that is much higher than the resistor doing the charging.

Mixos, I see the problem: In my e-mail, this part of the address is NOT highlighted: action=display;threadid=804;start=new Since this part directs my Outlook Express to the topic, it does not see it when I click on it, and sends me to the index instead.

Well, it has been over an hour and I did not get a notify e-mail about my own reply because that is fixed now. The previous notify e-mail sent me to the index page "General Feedback/Comments", instead of to this topic, like other web-site forums do. The e-mail was this: A reply has been posted to a topic you are watching. View it at http://www.electronics-lab.com/forum/index.php?board=4;action=display;threadid=804;start=new More replies may be posted, but you won't receive more email notifications until you read the replies Regards, The Electronics Lab Community team.

This is a test of "Notify of Replies". On my next post I will copy-and-paste the e-mail link and explain where it took me.

Mixos, Thank you, I have not seen a notify e-mail of my own reply all day today (previously every post that I made). I still hope that you are able to have the notify e-mail link to a thread instead of linking to the index.

MP, I didn't say that the author WILL update the circuit with my improvements, I said that he MAY do so, which is what he says. What is your concern about a filter in a Schmitt-trigger (with hysteresis) circuit? It makes a perfect time-delay, since the output responds exactly when the rising input voltage reaches its threshold.

MP, Sorry, no disrespect, but please make accurate statements. You don't believe that I corresponded with the author of this project? How's this: Hello, thank you for your suggestion. I will try the added capacitor and reconsider the whole circuit (which has been designed and prototyped more than 5 years ago and is no longer on my workbench). Unfortunately, however, I will not be able to do so until July, as now I am very busy and electronics design is not my job but only a hobby. In any case, thanks for choosing RED Free Circuit Designs Flavio.

MP, Where is the high-pass filter? Since when can a high-pass filter create a voltage pulse delay? I have been telling you all along that the circuit needs a delay, so that it can perform PWM on the NAND gate, causing the LED to dim. Maybe you don't understand the difference between a high-pass or low-pass filter, like your mis-understanding of NAND gate logic. Perhaps your translation software is giving you difficulties. But the capacitor that I have added creates a LOW-PASS filter, since it integrates the signal from the probe, and causes a delay. That small change will allow the project to work properly.

Dl, Do you want to build a random number generator?

Ante, I think that he is using this one. Siddharth, Am I correct?

Ante, Sorry, but The Rolling Stones were on my radio. ;D No disrespect.

Ante, Sure, that's real cool, man (or bloak, or mate!).

Here is my slightly modified schematic of this project:

Ante, That's nice, then James can see the display blinking to the pulses. But you don't know if the receiver can give enough power output. C, H and L? How about 2, 3 and 4?

Bob, Most DC motors stall with a HUGE current, just measure its resistance then use Ohm's Law. Isn't that why your circuit has current-limiting? So maybe you need just a decision: a) No current. The motor has burned-out. or b) Normal current. All is well. or c) Current-limit. The motor has stalled. You could even detect other problems such as: d) Low current. The drive-belt has broken. and e) Higher than normal current. Something is binding and the motor may over-heat.

Badai, You can build an EMI detector to prove to your crazy lecturer that only OPERATING appliances emit EMI, and maybe get bonus marks (or get expelled). You need a very-low-frequency AM receiver circuit. A normal AM broadcast band receiver will pick-up a bit of EMI when tuned to a quiet spot between radio-stations near the low end of the dial. It will be much better if you can pick-up frequencies that are much lower than that. Have you tried the simple Field Strength Meter circuit, but using a much bigger RFC (or 1K resistor) so that it picks-up lower frequencies? Our Projects Section has an Electronic Eavesdropping Detector project that may be suitable if you use much bigger capacitors for C4 and C6 (marked D1 by mistake) so that it picks-up lower frequencies. The project is here: http://www.electronics-lab.com/projects/rf/005/index.html But if you have any near-by radio or TV stations then the above circuits will pick them up instead, since they are not tuned.

Steven, Are they in parallel or in series? Since you like loud bangs then BE VERY CAREFUL and try powering-up a big electrolytic 1000uF/100V connected backwards to a high-current supply. If you are not injured too badly and can still hear, then you'll be cleaning it up for months.

Kasamiko, I think that you will find that your 3Kb to 6Kb is actually 3KB to 6KB, which is a mistake that I made when I replaced my built-in 14.4K modem with the 56K one. Windows gets the "b" and the "B" mixed-up sometimes. 1Kb in 15 minutes calculates to about 1.1Kb/sec, which does not agree with the above. 1) Make sure that your phone-line is clean (no hum nor static). One time I had hum and I complained to my phone company (post office, over there?). They used a high-tech cable-finder, and after digging-up my whole street finding cable-TV wires and old car-parts, they found the telco cable. A different company came and dug a hole that was 10 feet deep and huge. Then the 1st guy came back and made his splice and nearly got stuck down there when it rained. Then the digging company came back and filled the hole. Then another company came and replaced my grass. I'm not finished yet. Then the 1st guy came back because his office didn't record that the job was completed before. Each company sent 4 guys, one did the work and the other 3 supervised. This took nearly 2 months and didn't make any difference! 2) Find out which modem and speed of modem that your ISP is using, and set yours to match it. 3) Make sure that your modem is set-up correctly, for the modem and for Windows. Win '98 and newer defaults to DSL, not modem (maxMTU of 1500 instead of 576 for modem). 4) If your ISP's modem is newer than yours, then get an updated driver from your modem's manufacturer if they are still in business (mine wasn't). 5) The web is full of ways to tweak your settings. I tweaked my modem, then my high-speed settings, and got big improvements on both.

Steven, If all those capacitors are in parallel, instead of in series, then the "POP" sound is from them breaking-down, before you short them. Do you expect to have more than 14,490 volts (23 X 630)?

Yes, look at how neat and tidy his soldering is. He must have good eyes (or magnifying glass), steady hands and a small-tipped iron, or a tiny helper with those gifts.

Ante, Didn't you see my post?: Why re-invent a new circuit when this one will work fine with the addition of only ONE capacitor? For JLB and others who build this project, and want it to work at all with new batteries, or to have it continue functioning when its batteries are running down, and for a bonus have a much brighter LED, then simply repace its old IC with a newer and improved one. Isn't that constructive and are simple solutions to the problems? The author recently told me that he may update his circuit with my improvements when he has time in a couple of months.

Siddharth, You can't use a regulator as an on-off switch. It operates exactly the way that I said: With the base of the transistor high, then the regulator is floating and therefore will be a piece of wire from its input (15V) to its output, as in my quote #2 above. "The lights will be bright" because the output voltage will be high, as you see. With the base of your transistor low, then the output of the regulator will be 5V plus the base-emitter voltage of the transistor, as in my quote #3 above. "The lights will dim a bit but will not shut off" because the output voltage of the regulator will not be 0V, as you see. Never mind what MP said, he must be using faulty translation software.

Kasamiko, Actually, my 486 runs on twisted rubber bands! Yes, on cable I'm getting 1MB/sec, and the router for my LAN doesn't seem to slow it down, and even faster by using download-accelerator software. A 1MB PDF-file (nearly 200 pages) downloads so quickly that I can't read the speed on the accelerator's pop-up. My 56K modem was downloading at about 42Kb/sec but the accelerator boosted it to about 250Kb/sec. The accelerator has a "resume" function, so that if you are cut-off or just can't wait, it can continue a download later. If you don't have an accelerator then you must try one. Mine is called MetaProducts Download Express and is here: http://www.metaproducts.com/mp/mpProducts_Detail.asp?id=18 I'm using rev. 1.3.0.119 and it is so good that I won't upgrade. It might still be free.

The point of this discussion is not about the LED brightening (dimming in reverse) when the soil gets drier and drier, as the project's description says that it will. When looking at the LED today, can you determine whether its brightness is more than it was yesterday (I noticed that the LED was very dim yesterday), without having a standard LED to compare it to? Therefore another improvement would be for it to have a numeric display! The point is that JLB wants to use the project for a different function, but was relying on its description about dimming, which is extremely important to his function. He will probably have a bunch of circuits, side by side, and will see which one is brighter or dimmer.