Description: Probably made for a handy talky but I have no info regarding manufacturer or intended use. I built a DTMF decoder that I installed a socket on to match this encoder. Plug it in to test and set up. 12 button DTMF keypad works from 2.5-6 Volts with mute output which sources at least .5 ma with any key down. I accidentally left one on overnight with 13 V on it. It's working fine, speaks well of the chip design. Uses an 18 pin surface mount Sharp LR40872, which appears to be very similar to a Sharp LR4087BN. DTMF output is via a 2.2K pot to ground, a series cap, a series 4.7K resistor, and a cap to ground. Maximum single tone output @ 5 V with hiZ load is about 420 mv high group, and 320 mv low group. About half that with a 4.7K load. Four .025" square pins, spaced .1" provide the interface. Pin 1 is + 2.5-6 Volts. Pin 2 is ground. Pin 3 is DTMF out. Pin 4 is mute, high with any key depressed. It's 1.34" X 1.9", about .34" thick not counting pins. The left side has 2 outkicks, the lower right has a 2-56, .050 hex head screw which is captive but can be removed. Matte gray finish. Boxed individually.
Price: 18 USD
Location: Lakeside, Arizona
End Time: 2024-10-03T17:17:43.000Z
Shipping Cost: 0 USD
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Item Specifics
Restocking Fee: No
Return shipping will be paid by: Buyer
All returns accepted: Returns Accepted
Item must be returned within: 30 Days
Refund will be given as: Money Back
Brand: Unbranded/Generic
Type: dtmf keypad
Compatible Brand: Universal
MPN: 820-039-01
