diff --git a/Hardware_developement/4-HV/3-Flyback/Readme.txt b/Hardware_developement/4-HV/3-Flyback/Readme.txt
index f3c2269..17b8299 100644
--- a/Hardware_developement/4-HV/3-Flyback/Readme.txt
+++ b/Hardware_developement/4-HV/3-Flyback/Readme.txt
@@ -1 +1,4 @@
-The core of the flyback converter is a switching transistor and a resistor. The voltage supply, trafo, cascade and control (train of pulses) are all separate parts. In order to be able to quickly change transistors, flyback core is assembled on a protoboard. The whole high-voltage generator is then assembled from parts (see the photo).
\ No newline at end of file
+The core of the flyback converter is a switching transistor and a resistor. The voltage supply, trafo, cascade and control (train of pulses) are all separate parts. In order to be able to quickly change transistors, flyback core is assembled on a protoboard. The whole high-voltage generator is then assembled from parts (see the photo).
+
+The schematic is available in Fig. 12 in the following document
+https://o-esd.etf.bg.ac.rs/forgejo/dragan.olcan/O-ESD/raw/branch/main/Documents/O-ESD-02.pdf