The camera I use is a PC 164C video black and white camera (available from www.supercircuits.com). This is very sensitive - on a Meade 10 inch I can monitor down to something like magnitude 11.5, depending a little on the star type. The camera is more sensitive to red stars.

Meade 10 inch scope with camera attached	Close-up of PC164C camera

I record the video on a Panasonic NV-FJ630 VCR which is PAL and NTSC capable and appears to detect the NTSC nature of the camera automatically. I also have a small security monitor purchased from Jaycar (Satow 6" black and white). The videos play back OK on the tele set.

VCR, Monitor, and 286 laptop used to sync the GPS/KIWI timing system.

The monitor requires a 15v input, but a mains adaptor comes with it. The monitor also has a 12v output on the back which can be used to power the camera which requires 12v.

So the basic link-up is PC164C camera, replacing the eyepiece of a telescope, to the VCR and then to the monitor.

Since the PC164C has no built in mike, I have also added sound to the system. I have used a "lapel mike", I believe it is an "electret mic", as input into a small pre-amplifier, constructed from a very simple kit, again from Jaycar (KC5166: Pre-champ preamplifier kit) which seems to work OK. (I did find I had to use a separate power supply for the preamplifier, not take it off the 12V supply on the back of the monitor.) The preamplifier requires from 6v to 12v. The output can be fed into the VCR sound, from where it feeds into the monitor which has a speaker built in.

Using a GPS/KIWI system to get a time signal I can generate an accurate sound pulse each second, similar to the old VNG time signal, which I can then record with the image from the camera. I also add my own voice announcements of time for convenience - the minute and near the event every 10 seconds.

Camera, Monitor and GPS/KIWI timing box.

Lastly, since the laptop linked to GPS/KIWI also outputs a pulse which can be used to flash an LED in time with the time signal, I am feeding a red LED flash from it into the telescope (ie LED shines into the telescope objective). These flashes are useful if you want go through the video one frame at a time. The Panasonic VCR does not allow one to step through a video manually, but it can be played in slow motion, at just under 3 frames a second. This is a rate which can just be counted, so if you have a light flash on the second, you can count how many frames after a second marker an event occurs. The VCR displays 30 frames a second in this mode.

I understand Peter Nelson has a time register from Super Circuits (source of the camera). Provided one can synchronise this accurately to the GPS output, or some other accurate time output, this would almost certainly be easier to use than the simple light pulse as above.

Contact Brian Loader for further information.

[Top of Page][Return to Home Page]