Notify me of new posts via email. Why can’t you just drive M2 and get rid of the BJT? How to Build a Switch Mode Power Supply Circuit with an MC — Great tutorial and really helped me calculate the passive values by hand though his examples were vague in a few places. Adjustement was possible from to V. The timing capacitor was a 10 nF MKS2. Wish I had found this before. January 25, at
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The voltage could be adjusted from to volts. I am trying my best to keep the telco side extremely simple to decrease my chances of problems getting FCC certification if I ever manage to get that far. This board uses 1 x 2.
5V to 48V Switch-Mode Power Supply using MC | Big Dan the Blogging Man
Then what does M2 contribute? The function of the transistor is to increase the current when dischargeing the capacitor.
The used circuit here is a standard application, expanded by the ratio extender circuit as well as a high voltage switching transistor to isolate the controller MC from dangerously high voltages.
Input Voltage [V]
References First, here are some references: I have not tried this configuration myself and cannot offer any further advice! The picture below shows the long term drift.
28V Output From 12V DC Input Step Up DC-DC Converter Using MC34063
A lot of calculators out there suggest values, step-ul for higher voltages, these circuits fail. There are two question left mainly to be tested: This should serve to disable the ring signal for the connected handset without disabling the line for making calls or picking one up because you can hear a ring elsewhere or if you have ESP.
Big Dan the Blogging Man. Buy a lot of crystals: I am building a boost circuit, so the overall circuit layout will look like this: An extension, as described in Application Note by Onsemi is necessary.
MCA design tool
The next size inductor up I have is uH. December 13, at 8: I added a uF electrolytic cap and this seemed to reduce the ripple current, but it’s still very much discontinuous. I arbitrarily decide to use ped K ohm resistor for R2 so I just need to do some algebra to determine what R1 must be:.
You mayst also notice, that the output voltage is much higher, as ste-up as the input current is lower and the transistor gets not that hot.
January 25, at 6: