The TADD-2 Mini (or "T2-Mini") is a tiny frequency divider board that accepts a 1, 2.5, 5 or 10 MHz input signal and generates a 1 pulse-per-second ("PPS") output pulse. The pulse can be synchronized to an external source (such as a GPS receiver). The divider is implemented in a DIP-socketed PIC chip using software written by Tom Van Baak. The source code is freely available, and other software loads are available from Tom's web site to implement different division ratios.
Tests indicate that the jitter is in the range of 1 picosecond -- near the noise floor of the best test systems we've been able to configure. The input circuit is a wide-range design that works with signals from -20 to +13 dBm. The input may be high impedance, or terminated in 50 ohms via a jumper.
The T2-Mini has a single low-impedance output that delivers greater than 3.5 volts into a 50 ohm load, with rise time at the connector of less than 3 nanoseconds. In addition to the primary output, optional headers on the board provide either an LED or an auxiliary TTL-level output signal, and an inverted TTL-level pulse.
Power input is from 9 to 15 volts and current draw is from 20 to 50 milliamps, depending on output load.
An 8-pin header provides direct access to four of the PIC's pins; these may be used for configuration or additional input signals. The pre-programmed PIC that TAPR provides uses the 8 pin header to allow selection of four input frequencies -- 1, 2.5, 5, or 10 MHz -- and synchronization of the divider to an external clock source.
The board is only 0.75 by 2.0 inches and uses surface mount parts, although the PIC chip is a socketed 8 pin DIP to allow easy reprogramming.
AvailabilityThe T2-Mini is available now.
Because of the small size and tightly packed surface mount components, the TADD-2 Mini is available only with all SMT parts installed. The T2-Mini w/connectors includes the programmed PIC and other through hole parts which you must assemble to the board which already has the SMT parts installed.
The price for the T-2 Mini w/connectors is:
$ 49 US for members of TAPR
$ 55 US for non-members+ shipping/handling if applicable.
A note regarding email addresses: When checking out please use an
email address other than @earthlink.net, @hotmail.com, @live.com,
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Shipping and Handling
Shipping and Handling within the US will be by USPS Priority Mail.
International shipping costs are calculated as closely as possible. If the actual cost exceeds the estimate by more than $10.00, TAPR will contact you to get approval for the additional funds. TAPR uses insured Priority Mail International, unless the purchaser requires something else.
The T2-Mini Basic requires you to provide and program your own PIC chip. You must also provide your own connectors.
For information on ordering the T2-Mini basic, please contact the office.
Assembly and Operations Manual
The assembly and operations manual can be found online at http://www.tapr.org/~n8ur/T2_Mini_Manual.pdf.
Code as programmed in the PIC supplied in the T2-Mini kit w/connectors.
Other variations written by Tom Van Baak here.
The TAPR TADD-2 Mini was made possible by the efforts of:
John Ackermann, N8UR – Designer and Project Manager
Tom Van Baak – Software Author
Tom Van Baak
John Miles, KE5FX