cascading dc-dc converter mc34063

[TuralH]

 have assembled a cascade converter circuit. My main goal is to accumulate a voltage of 80 volts on a C6 1000uf capacitor in about 6-8 seconds. The problem is that I am using a 3.7 V battery. If I assemble a circuit with only one cascade and try to accumulate 80 volts from 3.7, then the energy accumulation occurs very slowly, that is, it takes about 20 seconds, but I have tried to do it with other DC-DC converters and it works, but the only problem, as it seemed to me, is that there should be capacitors with a large capacity between the converters. When I use this circuit, the voltage drops to 2 V instead of 10 volts. What could be the problem? In the peak current of the inductor or in the circuit itself? How else can I achieve this voltage of 80 volts for a 1000 UF capacitor?

[Andy Chee]

Don't double post

https://www.eevblog.com/forum/beginners/dc-dc-boost-convetter-cascade-(series)/

The obvious reason why it doesn't work is because the GND references between the two converters are common.  In order to have any chance of working, the GND references should be separate.