(a very cheap) DTMF Control Circuit via Radio --------------------------------------------- Use any 2-way radio to control a device remotely. Parts ----- Get 4 CM8870's by "borrowing" a Positive Account Verification Plus controller used by Schneider Communications or whatever they are called now. Notes ----- - Only controls ten devices - 3.58 MHz = 3.579545 MHz - Put LED's on the 8870's output lines and use a mic for input and you have a handheld DTMF decoder (with no memory) Truth Table 8870 Output 4028 Outputs Q4 Q3 Q2 Q1 DTMF key Q9 Q8 Q7 Q6 Q5 Q4 Q3 Q2 Q1 Q0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 0 0 0 0 D 0 0 0 0 0 0 0 0 0 1 0 0 0 1 1 0 0 0 0 0 0 0 0 1 0 0 0 1 0 2 0 0 0 0 0 0 0 1 0 0 0 0 1 1 3 0 0 0 0 0 0 1 0 0 0 0 1 0 0 4 0 0 0 0 0 1 0 0 0 0 0 1 0 1 5 0 0 0 0 1 0 0 0 0 0 0 1 1 0 6 0 0 0 1 0 0 0 0 0 0 0 1 1 1 7 0 0 1 0 0 0 0 0 0 0 1 0 0 0 8 0 1 0 0 0 0 0 0 0 0 1 0 0 1 9 1 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 1 * 0 0 0 0 0 0 0 0 0 0 1 1 0 0 # 0 0 0 0 0 0 0 0 0 0 1 1 0 1 A 0 0 0 0 0 0 0 0 0 0 1 1 1 0 B 0 0 0 0 0 0 0 0 0 0 1 1 1 1 C 0 0 0 0 0 0 0 0 0 0