diyAudio (
-   Power Supplies (
-   -   MC34063 blues (

astouffer 12th June 2009 02:25 AM

MC34063 blues
2 Attachment(s)
Can anyone help me figure out why this circuit with an MC34063 is not working correctly? I followed the datasheet and also used the design tool to try and boost 12 volts up to 20.

Without a load the voltage slowly creeps up to about 18 and then drops with even a few milliamps applied. My first inductor was a 100uH toroid which I thought was too low so I changed it for a 250uH ferrite core choke. Then I lowered the timing cap from 220pF to 100pF to increase the switching frequency, that also had little effect.

Any ideas as to whats wrong?

astouffer 12th June 2009 02:28 AM

2 Attachment(s)
Here is the pcb layout in case thats an issue. Red is the top layer and blue is the bottom.

star882 12th June 2009 02:41 AM

The inductor needs to connect before the 180R resistor.

astouffer 12th June 2009 01:23 PM


Many thanks, thats been bothering me for a while. :smash:

All times are GMT. The time now is 11:28 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2