🚀 go-pugleaf

Polaroid uses an ultrasonic transducer in their instamatic cameras.  The
Specs are as follows:

Distance Range:				0.26 to 10.7m (0.9-35 ft)
Resolution:				1% over entire range, 3mm up to 3m
Beam Angle: 				12 degrees (typical, at 3dB down)
Transducer Drive Signal -
   Gated Sine Wave			50kHz
   Duration				1.1 ms
   Suggested Drive Voltage (peak)   	150v
   Bias Level				150vdc
   Maximum Drive Voltage (ned) 	400v
Min transmitting sensitivity at 50kHz	110dB
Min receiving sensitivity at 50kHz	-42dB
Power Requirements
   Voltage				4.8-6.8vDC
   Current				2.5A (1ms pulse)
					150mA (Quiescent)
Weight					
   Transducer				8.2gm
   Modules				18.4gm

Dimensions
   Thickness				0.46 in.
   Diameter				1.69 in.


The more expensive autofocus mechanisms actually focus the camera instead
of just deciding how far away the subject is.  They do this by measuring
the intensity of the focused beam in 3 tightly spaced planes:

				|  |  |
				|  |  |	
				|  |  |

if the camera is focused properly,  the intensity of the light on the center
plane is greater than the 2 surrounding planes.  Play with a magnifying glass
for a while, you'll figure it out.

If anyone is interested in ultrasonic transducers, Polariod does sell them.
Polaroid offers 2 kits, The following is a quote from their brochure:

	The Designer's Kit.  to help~r you explore the fascinating poten
	of this unique product, Polaroid has developed an Ultrasonic
	Ranging System Designer's Kit.  The kit contains everything you need
	to start experimenting on your own:  a technical manual. application
	notes, one instrument grade transducer, an ultrasonic ranging circuit
	board, an experimental demonstration board with led display, 2 Polaroid
	polapulse batteries, wires and connectors. $165*

	The OEM Kit.  Ideal for the hobbiest or student for prototype 
	development.  This kit contains two instrument grade transducers,
	two ranging circuit boards and cables, a technical manual and
	application notes. $99*

	Components.  Transducers, ranging circuit boards, cables, ran
	board subcomponents (transformers, coils, IC chips, and resonators)
	are available in minimum quantities of ten.

	*Prices subject to change without notice.

Polaroid's address is:
	Polaroid Corporation
	119 Windsor Street
	Cambridge, Massachusettes 02139

	617 577 4681
     	Fax: 617 577 3213


If anyone is interested in half (or more) of an OEM kit, let me know.  If 
there is enough interest, maybe I can place a bulk order.  I don't know what
kind of discount I can get.

E-mail can be sent to
	Jim Malloy
	C/O K Lambrecht

or I can be reached by phone at 703 335 2774 (home)