scottnj said:
I have a 4 button remote control. I want to incorporate this functionality into my own project. The main IC is a MC145026D, which I have found the datasheet for.
So I'm assuming you want to reverse engineer this circuit which will be quite hard to do, but how about the reciever?
The RF of the circuit will need to be exactly the same layout as the module in order for it to work properly, forget about using vero board - it simply won't work and you might need to used surface mount componants for it to work.
I can get the same IC (dip, not surface mount).
Then I guess I need to match the clock rate.
I also need to find out what frequency this transmits at, then I can just find a transmitter module that matches.
Wait, is this circuit a transmitter or a reciever? It looks like a transmitter to me, but you've asked for a transmitter module that matches it ??? is this just a typo didn't you mean you need a reciever module?
How can I figure out what frequency this transmits at?
What is the clock rate?
With a frequency counter.
A scanner could be used to deturmine the RF frequency but I guess it's between 300MHz and 1GHz may be even hight but it'll probably be about 433MHz.
What are the other surface mounted components?
They are:
- blue with numbers
- black with numbers
- light brown with what looks like Y0
- brown
- silver
Small surface mount capacitors and three legged devices are often unmarked so I'll do my best for you.
Transistors: ?1, ?3, RA4E
RF Transistor: 3E
I can't tell whether the transistors are bipolar, NPN, PNP MOSFET or JUGFET - but you can conduct tests on them and reverse engineer the circuit more by looking at the connections and if you're experianced enough you might be able to guess.
Surface mount resistors are marked with their value followed by the number of zeros on the end:
154: 150k resistor
623: 6k2 resistor
181: 180R resistor
104: 100K resistor
1002: 10K presision resistor
The tollerance of the reisitors is normally 1% for units marked with 3 numbers and 0.1% for those with 4 numbers.
Capacitors - as they're unmarked I'll try to guess their approximate values from the layout but I strongly recommend you measure them removed from the circuit with a capacitance meter.
?2, ?4 about 100nf decoupling capacitors - not criticle
?5 - no idea.
?6 - 1pf to 10pf - likely to be a RF bypass capacitor on the RF oscillator.
Y0 - 1pf to 33pf - possibly a part of the tuned circuit and will depend on the frequency.
I forgot to mention, I do not have an oscilloscope.
Good luck, this is hard enough to do anyway but you'll need a lot of luck if you don't have a very good oscillosope.
