diff --git a/extras/pcb/README.md b/extras/pcb/README.md
index 9b7099e..bdc7b33 100644
--- a/extras/pcb/README.md
+++ b/extras/pcb/README.md
@@ -10,7 +10,7 @@
 
 ![image](https://dl.dropboxusercontent.com/s/w89ivzvuzk6hf5b/famicom_adapter.png?dl=1)   
 
-#### sms_adapter.zip is an add-on for reading Sega Master System carts. You can order a 2.54mm 50pin SMS slot [here](https://www.aliexpress.com/item/32818469880.html). Ignore the SMD footprints on the PCB, the adapter does not need any components.    
+#### sms_adapter.zip is an add-on for reading Sega Master System carts. You can order a 2.54mm 50pin SMS slot [here](https://www.aliexpress.com/item/32818469880.html). The adapter is based on the [design by Raphnet](https://www.raphnet.net/electronique/sms_to_smd/index_en.php). For use with the Cart Reader ignore the SMD footprints on the PCB, the adapter does not need any components. I only bridges R5 to connect the reset line, although I'm not sure if this is even needed.    
 
 ![image](https://dl.dropboxusercontent.com/s/r6lavgoaccjtrz7/sms_adapter.png?dl=1)