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  1. Olihou

    ECG for home use

    Here is one circuit I have found from : Has any one tried it out? How good can it perform ? I would like to have some assurance of the circuit before trying to search for the parts, the op amps in particular, which seem to be unavailable locally. Will any one please advise. :o Oli
  2. Olihou

    ECG for home use

    Hi Audioguru Thanks for your advice. The only thing I do not understand is that why I should be wearing a white doctor's gown. ::) I have started searching for the instrumentation amp, but am not successful yet from local suppliers I have checked. I will continue to search for it. I do need...
  3. Olihou

    ECG for home use

    Hi Audioguru Thank you very much for your advice. You have always been so nice and helpful. My interest in ECG arises from my curiosity, and most probably due to my childhood desire to become a medical doctor, but that has been only a dream for me. I just wish to find out if a ECG can reveal...
  4. Olihou

    ECG for home use

    I have found a circuit at the website of Scientific America: http://www.sciam.com/article.cfm?articleID=000C74E4-5172-1C74-9B81809EC588EF21&pageNumber=1&catID=2 The ECG circuit seems to be surprisingly simple. Would it really work -- I wonder. Any one has tried this circuit? Or any...
  5. Olihou

    ECG for home use

    Hello every body! I am new to this forum. I wish to build a simple ECG (Electrocardiograph, for one of my family members not having a good heart). This project does not seem to have been a topic of discussion in this forum. Can any one advise me how I should start. If any one can provide me...
  6. Olihou

    Question on the Plants Watering Watcher circuit

    Hi Audioguru Of course not as, any pure water getting into contact with the dirty soil will become not pure. Minerals in the soil will certainly be dissolved in water. I wonder if there is any "soil" without minerals. If there is, then it is not suitable for plants -- plants need nutritions...
  7. Olihou

    Question on the Plants Watering Watcher circuit

    Hi Audioguru In my place I am given to know that commercial "distilled water" is not trully fully distilled -- there are still minerals such NaCl as ions which makes water conductive. Even if it is 100% distilled and free of minerals, there are still likely minerals in the soil. So there is...
  8. Olihou

    Question on the Plants Watering Watcher circuit

    Dear Audioguru Thanks for your comments. I hope you do not mind that I have not follow your design faithfully. I have just used parts readily available. Hence the electrical performance is different from what you have built. :( However functionally I trust it is as good as yours. :) As a...
  9. Olihou

    Question on the Plants Watering Watcher circuit

    Dear Audioguru I have obtained the following measurement results: Ohm between probes On Pulse of LED Battery Current ---------------------------- -------------------- ------------------- 47 Nil on scope 0.6 mA 100...
  10. Olihou

    Question on the Plants Watering Watcher circuit

    Dear Audioguru Thanks for your comments on the LED. Mine is really one with a beam of very narrow angle and I will look for a replacement. I think that current consumption might not be a problem for the resistance-to-flash-rate option, as we could control by design a low flash rate to reduce...
  11. Olihou

    Question on the Plants Watering Watcher circuit

    Dear Audioguru Thanks for your prompt reply. I will check the performance of my LED. It is one with unknown part number, just picked up from the shelf. I agree that as you said "It would be fairly easy to make it flash very slowly when the resistance is high (dry soil) and flash quickly when...
  12. Olihou

    Question on the Plants Watering Watcher circuit

    Dear Audioguru I have succeeded in building the unit according to your design. It is working exactly as you have described. I am completely satisfied with the circuit, except that the brightness of LED does not seem to give a clear indication of the level of dryness. The LED I have used is of...
  13. Olihou

    Question on the Plants Watering Watcher circuit

    Dear Audioguru I have read through the conversations in one breath. The subject is of much interest to me as a electronics amateur and plant lover. You have really done a good job! I will certainly try out your circuit shortly. Thank you very much!
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