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  1. Olihou

    UVB Meter

    At last I have been able to find locally a supply of UV sensor diodes OS100 from Orion Semiconductor:  http://www.orion-semi.com/orionsemi.html I have tried it out, giving a few mV output when shined with a small UV lamp used for checking bank notes. Will look for suitable circuits to make a...
  2. Olihou

    UVB Meter

    Thanks OnOff. 6490 is probably OK for my application, except I am not sure how its unit :Index has been defined. I would prefer the unit uW/cm2. Besides, being a module with the amplifier the price will probably be high. I would prefer having a sensor diode and build the circuit my self. It...
  3. Olihou

    UVB Meter

    I have the interest to build a UVB meter for measuring the ultraviolet radiation intensity in the wavelength range from 280 to 320 nanometer. It will be used in my reptile house. The reptiles need UVB light for making vitamin D for bone health, but over doze will hurt them. UV meters are...
  4. Olihou

    Computerized Monitoring of ECG.

    Hello Jedi As an amateur I have the interesrt in building an ECG machine, and have now completed the basic amplifier circuit to acquire the ECG signal from my own body. Please see my previous posting in this forum: http://www.electronics-lab.com/forum/index.php?topic=1746.0 What I like to do...
  5. Olihou

    Electronic Eavesdropping Devices Detector

    I see. Thanks a lot Audioguru !
  6. Olihou

    Electronic Eavesdropping Devices Detector

    Hi Audioguru and every body I am curious at the thinking that kit-makers put errors in their products purposely -- and if the kits would not work -- would that defeat their intention to sell the kits  -- so they have protected their intellectual properties -- but not their businesses ? I have...
  7. Olihou

    PC Chart Recorder

    Thanks Ante. I will try what you have recommended. I am now exploring Labview. I have already downloaded the program but it seems quite sophisticated that I need to spent some time to find out how it can be used. Oli
  8. Olihou

    Log voltmeter

    Hello Lou How about this? See if it helps. http://www.national.com/an/AN/AN-30.pdf The log amplifier output gives a DB equivalent of the input voltage. An ADC would be required should you need the digital form. Oli
  9. Olihou

    PC Chart Recorder

    YES ??????
  10. Olihou

    PC Chart Recorder

    Any one any advice please ? Just tell me if you are aware of any programme for Windows to convert a PC to a chart recorder -- Yes or no please? Oli
  11. Olihou

    Log voltmeter

    Is the output you have in mind digital or analog? If just for analog, there are functional circuits using op amps and diodes, as far as I can recall. Have you search for it in the cyber?
  12. Olihou

    Physics Project in need of some expertise

    Your requirement is not very clear to most readers, I am afraid. Perhaps you can describe what your physics experiment is so that others will know what you really want. Also a block diagram of the circuit you like to have should help. Oli
  13. Olihou

    voltage divider for AC

    I have some experience in powering low power circuits directly from 220V mains, without the use of a power transformer. Voltage regulation could be achieved by the use of zener diodes Darrins needs to tell others what kind of device/circuit he/she intends to power before others can offer...
  14. Olihou

    PC Chart Recorder

    Hi Does any one konw if there is any programme (preferrably free) for Windows to convert a PC to a chart recorder, using the audio card as the signal input? I have tried some programs for PC oscilloscope. However their time base is not long enough for recording signals for long time, say...
  15. Olihou

    Question on the Plants Watering Watcher circuit

    Hello dicky Dimming by a trim-pot? What do you mean? What do you want to do? Oli?
  16. Olihou

    ECG for home use

    They prices are in US$, and are quoted by Farnell in HK$297 and HK$79 respectively. It is expensive ! I think I will take Audioguru's advice and try the TL072 or other popular opamps first. However I can foresee that much circuit skill would be needed to get it perform, in say achieving good...
  17. Olihou

    ECG for home use

    They prices are in US$, and are quoted by Farnell in HK$297 and HK$79 respectively. It is expensive ! I think I will take Audioguru's advice and try the TL072 or other popular opamps first. However I can foresee that much circuit skill would be needed to get it perform, in say achieving good...
  18. Olihou

    Electronic Stethoscope 2

    Hi Audioguru Congratulations! You have made a good stuff again! By the way, I undersdtand that we have a university here conducting an R&D project on electronic stethoscope. It is said that the new device have many good features and would evetually replace the traditional mechanical ones...
  19. Olihou

    ECG for home use

    Thanks Trigger and Audioguru ! With your advice I have now been able to locate the suppliers locally. The AD624AD cost $38. The INA118PB costs $10. Surprisingly INA118PB seems to have better specifications! I will certainly use INA118PB! I just wonder if AD624 is something out of production...
  20. Olihou

    ECG for home use

    Dear Audioguru I am in a small place south of China, ruled by British for one hundred years until 1997 when it is returned to China. Got it? ;) I have been searching for the inamps. They are available locally only in large quantities! So I am still thinking if I can use opamps readily...
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