A quick question about the DC-DC step up circuit used on the bluerotary board. Acording to the schematic, a MC34063 chip is used. I have bought this chip with the intent to play with the blue rotary board.
The problem I’m having is that initially, the step up was working fine, generating ~55V from the input voltage. However, after a few minutes, the step up circuit stopped working, the output voltage was about 1V .
After replacing some of the other components I eventually replaced the MC34063 with a new one. On applying power, 55V was created, but then after about 20 seconds, the same thing happened.
Any help would be much appreciated! I’m running out of MC34063 chips!
I built this circuit using the POR schematic, and it works fine for me. I also compared the schematic to the datasheet, and it appears to be correct. That leaves a couple of possibilities:
A wiring error
A component error (value, etc.)
An output error (you’re drawing too much current, etc.)
Since it works initially, #1 is not too likely, but check anyway. #2 is possible, so check this as well.
What is the output driving, if anything?? Try not connecting to anything if you haven’t already.
Does the device get hot before it fails?
My guess is that you are damaging the output stage of the boost converter, but that’s just an educated guess.
My problem occurred when I started drawing current through the 55V.
Do you think that the MC34063’s that I’ve used are now broken? Should I instead try to replace all other components namely the resistors and capacitors.
Any idea which of these components would be likely to fail?
The MC34063 step up chip can only produce a maximum of 40V output. The schematic for the Ringer circuit on the Sparkfun website causes the chip to generate 55V which is well outside of spec.
Any idea as to why this is the case? Does SF use a higher rated chip than the MC34063 in the BlueRotary Product?
In the meantime, i’ll see if my ringer will work with a voltage lower than 55V