I'd like to build a 433 MHz receiver from scratch. Is there a schematic or some material to learn how to build one?
Google search didn't come up with much in the way of building one from scratch.
Electronic – 433 MHz receiver
433mhzreceiver
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Are you sure that your module works well to 12 V?
Since it is the "XY-MK-5V" model I think it has the voltage up to 5 V as ideal.
For all I know, these modules work well between 3.3 V and 5 V, maybe saturating the circuit.
Really, the transmitter work with up to 12 V.
But I suspect that it does not work at the frequency in question. See, there are a lot of bad information on the Internet about them.
- Product Model: MX-FS-03V
- Launch distance: 20-200 meters (different voltage, different results)
- Operating voltage: 3.5-12 V
- Dimensions: 19 * 19 mm
- Operating mode: AM
- Transfer rate: 4 KB/s
- Transmitting power: 10 mW
- Transmitting frequency: 315 MHz
- An external antenna: 25 cm ordinary multi-core or single-core line
- Product Model: MX-05V
- Operating voltage: DC5V
- Quiescent Current: 4 mA
- Receiving frequency:315 MHz
- Receiver sensitivity:-105 dB
See more at: How to use 315 MHz RF transmitter and receiver modules with an Arduino
I tried those antennae and I got better range with a whip antenna made from 17cm of copper wire. Probably 1/3 to 1/2 better. Like you I'm combining an ATTiny85 and 433mhz transmitter. The transmitter definitely works better with 12V though it works quite well on 4.5V with good line of sight over about 40m for me. When I tried a 7085 in my circuit the 12v battery did not last many hours (about 6? I left it overnight and it was dead in the morning). I did not use an NPN, I just connected the data from the transmitter to one of the ATTiny pins. It worked fine except for the battery drain which I am still trying to solve.
Best Answer
Sorry that I can't point you to an answer, but I can shed some light on why Google doesn't come up with much (my response is too long for a comment). The reason is very few designers have access to the equipment necessary to properly design a 433MHz circuit from scratch. Normal oscilloscopes are definitely out, and every little 0.1mm corner of a pad of your circuit board is actually a tiny inductor and capacitor connected to every other part of your circuit (parasitic/stray inductances and capacitances are killer at frequencies that high).
Also, the schematic of a 433MHz design is impossible to divorce from the geometry of the PCB layout. In other words, they would have to give you the schematic as well as the exact PCB geometry to make it work. Also, unfortunately, hand soldering is out due to parasitics. (Soldering an antenna on is one thing, but soldering the whole board is going to completely change the response of the circuit).
I don't mean to discourage you. I just want to make sure you know you're trying to slay a very big giant.