MX-RM-5V / RF-5V

Super-Regenerative ASK (Digital AM) Receiver

The MX-RM-5V breakout board is the European 433.92MHz version, and the RF-5V is the US 315MHz version.

The board is sometimes labeled XY-MK-5V.

It is primarily used in remote control solutions.

Design Flaws

This receiver has a very simple receiver architecture: an oscillating L-C circuit is connected to a LM358 OpAmp. Receiving a signal drives the OpAmp into saturation.

While sensitivity is reasonable, selectivity is not. This receiver is easily jammed by strong signals, even when these signals are transmitted on a completely different frequency.

For example, when a device closer than 20cm to this receiver emits a WiFi signal, then this can be enough to render this receiver unusable: it won’t pick up any legit signals anymore.

It may in fact be enough to mount this receiver close to a large capacitor to deafening it.

Receivers based on advanced receiver chips such as SYN470 or SYN480 are much more reliable.


Two versions exist:

  • 315MHz (US market): this board is marked RF-5V on the back side. On the front side, a big 0.5W resistor is soldered on the board.
  • 433.92MHz (European market): this board is marked MX-RM-5V on the back. There is no big resistor soldered on the front side.


The board exposes four pins that are labeled on the back:

Pin Label Description
1 GND negative voltage
2,3 DATA Data Out
4 VCC 5V

Make sure the power supply is properly filtered and carries no exceptional noise which could interfere and distort reception.


This receiver can be operated without an antenna (which limits reception to just a few meters). For better reception, an antenna must be soldered.

Here is how to create a simple coil-loaded antenna.

The antenna needs to be soldered to the unmarked through-hole connector on the lower right edge of the board, next to the inductive loop.

Make sure your board has a soldered copper inductive loop has three windings. There have been reports of partially incorrectly assembled boards that use the eight winding coils designed for the transmitter board.

Technical Data

Item Description
Voltage 3-8V, 5V preferred
Current fully operational 4mA
Frequency 315MHz or 433.92MHz
RX Sensitivity -105dBm
Modulation ASK (AM)
Data rate <10kbps
Distance few feet (w/o antenna), 30-50m (with antenna)
Size 30.3x13.8x7mm


Please do leave comments below. I am using utteran.ce, an open-source and ad-free light-weight commenting system.

Here is how your comments are stored

Whenever you leave a comment, a new github issue is created on your behalf.

  • All comments become trackable issues in the Github Issues section, and I (and you) can follow up on them.

  • There is no third-party provider, no disrupting ads, and everything remains transparent inside github.

Github Users Yes, Spammers No

To keep spammers out and comments attributable, all you do is log in using your (free) github account and grant the permission to submit issues on your behalf.

If you don’t have a github account yet, go get yourself one - it’s free and simple.

If for any reason you do not feel comfortable with letting the commenting system submit issues for you, then visit Github Issues directly, i.e. by clicking the red button Submit Issue at the bottom of each page, and submit your issue manually. You control everything.


For chit-chat and quick questions, feel free to visit and participate in Discussions. They work much like classic forums or bulletin boards. Just keep in mind: your valued input isn’t equally well trackable there.

  Show on Github    Submit Issue

(content created Apr 18, 2024)