trigger

2.4GHz ISM band is a bit difficult for me esp. to build transmitter, because it involves a lot of matching problem. Although you can build using simple LC+transistor circuit but if you don't have a spectrum analyzer or signal generator, it will not an easy job. For me, I will start with 433.92MHz where it is simple and need lesser equipments esp. you can build a transmitter using saw resonator and a transistor based receiver.

Would like to know if there are any good websites about AM/FM tuning methods......? Although I have worked on this stuff for quite a few years, I still keep on trial-and-error methods for fine tuning..... And what are the sensitivities standard for AM/FM radio?? (I have several info but different factories have differenct standard........) Anyway, Thanks first ;D

It depends how complex your PCB is and the components you are choosing (through hole or SMT)..... For my experience, try to put connected components closed together and try to route tracks through gaps of components (except IC pins).... But don't expect the auto-route function can give you much help, it always give you trouble

Think of the followings: 1. Transmit distance 2. Transmit frequency 3. Transmit modulation (AM, FM, etc) 4. Bandwidth/ data rate of the commands Hope these give you some insight... ;D

if you have a chance in access a spectrum analyzer, you will noticed that the cell phone isn't transmit continuously. I suggested if you want to use the RF signal as the sourcce, you can use RF scottkey diode to pick up the RF signal, and sample its presence in a certain period of time, say for example 1s. Hope this help

I think build your own IDE interface from scratch isn;t that easy...... may be you can consider to use some interfacing chip .....

Please noted that the cell phone does not transmit RF signal continuously during calling...... thus you cannot use the RF signal as the indication of call time..... just my opinion. ;D

For a movement trigger switch, I think you can disassemle a sport step-counter (hmm...... some of them use mercury switch or magnetic switch, but nowadays most use an arm+drum+spring wire due to thier low cost) and take out the mechanism......... I will take a picture of that mechanism later and post here ;D

Thanks audioguru, that takes my a lesson to learn :) Actually, I know the problem as the circuits will gives me a blinking while the DC level is about the threshold level..... so finally I come up with a schemitt trigger circuit to have a voltage comparison, and give either a logic 1 or 0 to the diac. But for controlling the motor may be a big different from that of a light bulb..... so let see who will have a better solution... ;D

That reminds me my old time in primary school............ I disassembled batteries and take out the graphite, connected two with supply and dipped into a cup of salt water...... I used test tube to fill with hydrogen and oxygen come out from the graphite.... My game is lite a match to make a pop sound......... But the remains of water is dirty....... :P

I think TRIAC + DIAC can do the high voltage switching without a spark....... I have done projects in 100W light bulb switching using LDR as sensor at 220Vac. The switch on and off depends upon the DC level to the DIAC. So if needed the circuit I can draw them out........ (or you can google search..... should find in many free schematic sites )

Seems your company located in Hong Kong, just as I do.......... So will you be able to provide PCB samples ordering....... (without Mass production.......)

........... ah......... who knows...... just it comes with a pack of batteries as an add-on gift but I will try check its output frequency

I have disassembled a cheap mosquitos repeller. it just use 2 transistors, a few R and C, and a piezo buzzer.... May be later, I trace and draw the circuit out....