G'day all.
Thanks for all shared knowledge in response to my camera/monitor project, I am learning a great deal as I read!
With outdoor cameras, whilst my camera is not exactly battery operated portable, I could stick a hood over it all and work it outside the garage.
In the meantime I am still yet to get the image pickup sensitive enough to even film natural sunlight which is what this post is going to be mainly about.
I have since added a cardboard hood to the condenser lens/phototransistor sensor unit to keep stray light out and have added some black tape to cover the exposed area of the less domed condenser lens so only light from the holes in the disc hit the phototransistor. And of course I have been doing more testing and have added another 4 stages of amplification to the head amp in hope to make the image pickup more sensitive to lower light.
Unfortunately with image sensitivity I have hit a stumbling block.
Initially the head amp consisted of 3 stages of amplification, first stage was this circuit
http://www.hawestv.com/mtv_cam/mtv_cama ... ansAmp.png (transistor Q2 is BC548), then I added 2 snaptogether stages PNP then NPN using these circuits
http://www.hawestv.com/mtv_cam/mtv_camart/addAnAmp.png (transistors of choice were BC547s and BC557s). Now with 3 stage amplification, it was sensitive enough to pick up bright light from my torch and from the 150W incandescent lamp shining directly into the lens and reflected metallic objects like the shaft of a screwdriver.
But I could not get the phototransistor to work with just shining the 150W lamps onto general objects, still not bright enough for it. So I decided to add another 4 more stages of amplification once again using those snaptogether stages
http://www.hawestv.com/mtv_cam/mtv_camart/addAnAmp.png and using BC547 and BC557 transistors and tested it out again. Unfortunately that did not increase the sensitivity of the image pickup from the phototransistor and of course with this amount of amplification I was getting unwanted signal noise going to the LED driver circuit causing it to intermittently flash, so I rolled the amplification back a couple of stages which fixed that issue, so my head amp now consists of 5 stages. But with 5 stages the image pickup is no better in sensitivity than that of 3 stage amplification.
So it now makes me wonder, are phototransistors poor image sensors or do they vary greatly in sensitivity depending on what one you buy? The phototransistor I am using is a L-51P3C bought from Jaycar
http://www.jaycar.com.au/productView.asp?ID=ZD1950 (see attached pdf for its details). When I did some basic testing with this phototransistor I found that for the oscilloscope to even display a signal on it I literally had to shine the torch directly over it and it seems to have a hard on almost "digital" response to light as in light or no light instead of the desired "analog" response to light with varying levels to create a picture of varying light levels.
Also I wonder a solar cell from a calculator or a general purpose light dependent resistor have better light sensitivity and could they easily be adapted to the head amp without modification? And hearing that dome sensors seem to be the image pickup sensor of choice for NBTV camera makers, what are typical dome sensor model numbers and where does one buy a dome sensor from as I don't seem to see them commercially available on Jaycar nor even on Ebay? On both Jaycar and Ebay search the results are security cameras housed in dark tinted domes.