PAGE 2 of 2 - PICKIT 3 External Dual Power Supply (3v3-5V) PCB
Parts and PCB
Here are the parts and the PCB that i used for this project:
First, i had to modify some parts for my design. I got some long 0.1'' pitch connectors. These have to be kinda longer than the normal 0.1'' ones. With a pair of pliers i bended to 90 degrees. I also moded a slide switch. With the cutter i removed one terminal that was not nessecary:
I decided not to print a PCB for this project. Instead, i used a perforated PCB that i had in stock some 15 years...
|I cut the PCB to the final dimensions
||With the dremel i had to do some cuts on the lines
Then i soldered the parts onto the PCB. I used an old Nokia charger to provide power to the circuit. It can provide as much as 750mA at 6.5V.
This is the idea:
A final touch
And then i decided to add an LED just to indicate if the circuit is under power or not. A simple green LED with a 220 Ohms resistor connected to the output of the circuit will do the trick:
|Just a green LED and a 220 Ohms resistor
||I trimmed one lead of the resistor and one lead of the LED
||And then i soldered them in series...
Finally, this is what i got:
Testing the results
Testing the output for 5V and 3.3V with the Fluke 87V:
|5.1V - Its like 0.1V more but still well within the acceptable range
||3.3V - It performs perfect at 3.3V
|At 18 May 2014, 4:29:23 user Cristi wrote: [reply @ Cristi]|
Hello. Idea is OK, but not necessarily quite discontinuing of Vcc from pickit3?
At 24 September 2013, 19:11:30 user jdraughn wrote: [reply @ jdraughn]
You might want to insure that the switch you use is a make before break, otherwise the voltage will spike as you switch from one voltage to another.
At 23 September 2013, 21:20:51 user solipso wrote: [reply @ solipso]
Nevertheless, the idea is great as we, lazy dogs, always like to power our PIC circuits directly from PICKIT - regardless the current needed. Your hack justifies this bad habit and makes us look a bit less silly, though.
I also like these switches very much, especially with multiple poles and with good contacts (surely not those eBay cheapies with 0.3 to 0.7 Ohm ON resistasnce).
At 23 September 2013, 17:09:18 user Giorgos Lazaridis wrote: [reply @ Giorgos Lazaridis]
@solipso My original design involved a HDD jumper. Jumper ON means 5V, otherwise 3.3. It was safe enough, but then i saw my stock bin with these sweet slide switches... I just could not resist.
At 23 September 2013, 13:58:58 user solipso wrote: [reply @ solipso]
Surely it does! :-) Nevertheless, this is based on my very own experience. I have had something like this on my breadboard PSU and I killed quite a lot of devices stupid enough to get killed by humble 5V before I realized to shorten the lever to about 3mm, which proved to be enough to switch easily, but intentionaly only.
At 23 September 2013, 13:50:38 user Giorgos Lazaridis wrote: [reply @ Giorgos Lazaridis]
@solipso And this makes things more interesting, doesn't it???
At 23 September 2013, 12:16:23 user solipso wrote: [reply @ solipso]
The long protruding lever of the voltage switch literally asks to be switched to 5V when the rig is connected to 3V3 micro and let the magic smoke escape free.
HOT in heaven!