Tuesday, May 24, 2011
I haven't done a video in a while, here is a review of the Astron Linear Power supply 20 Amp @ 13.6Volts. This supply in the video I bought about 20 years ago at a HAM radio flea market and just recently dropped it by accident six feet onto a concrete floor...oops. Will it work??? see what happened in the video. Tear down time!
Wednesday, May 18, 2011
Well anyway back into electronics here is a project I think is number one piece of equipment you should build a Triple Power Supply bench top laboratory grade supply. There are plenty of kits out there for the beginner, if your more advanced you can build your own from scratch. I would recommend LINEAR 5 Volt at a couple of amps and dual +/- 15 Volt at about 1 or 2 amps at most. This will cover about 99% of the items you breadboard up and test. Below are some pictures
25 turn potentiometers, to get in fine voltages
Heat sink are part of copper substrate (about 2 sq inches under chip)
Added AL heat-sink (not pictured)
PM128-E meter, enhanced pm128 with common ground feature so I can tap off the 5 volts to power
the LCD display instead of using a 9 volt battery like in the regular pm-128's
+/- 0-15 Volts (LM317,LM337) and fixed 5V (LM7805)
Two big filter caps 1500uF at 100 Volt
four heavy 6 amp rectifier diodes (way more than I need)
This is an old version a current version we are going to use next school year is an arduino based display, our old display PM-128E cost about $20 and only displays one voltage at a time. With and arduino based screen we will have 20X4 Blue LCD display all three voltages at the same time and all three current outputs and at less cost about $5 to $10. The display first displays a splash screen with the student name and year of grad and email for 10 second on start up then displays this:
SSVT TPS Model 101
V1 XX.XXV I1 XX.XXmA
V2 XX.XXV I2 XX.XXmA
V3 XX.XXV I3 XX.XXmA
Tuesday, May 17, 2011
Sunday, May 8, 2011
I designed this for our Arduino based triple power supply. The supply is a bench top linear supply with a 20X4 LCD screen. Displayed on the screen is voltage V1,V2 and V3. Easy enough to monitor with the Arduino A/D converter with a basic voltage divider. However to monitor current we needed a current to voltage monitor, I searched the web and found some current to voltage monitors but there were not cheap, cost was around 30 bucks. My design this cost around $5 USD.
The heart of this circuit is the LMP8603 a 60V Common Mode, 100 x Gain Bidirectional Precision Current Sensing Amplifier. With a very small value resistor to get around the burden voltage. I used a .01 ohm resistor that could measure 0 to 5 amps at 0 to 50mV across the resistor then added the LMP8603 with a gain of 100 so for every amp I would get 1 volt out.
The great thing about this IC, it's bi directional, it can be a high side or a low side configuration. It uses a single supply, A set gain of a hundred with no precision resistor needed like standard op amps.
Resolution of this is around 5V(A) / 1024 (10bit A/D) = 4.8 mA per step, if you need to change the resolution you could always swap out the resistor with a .1 Ohm but you maximum current would only be .5 amps, but resolution would increase to .48 mA per step. For my case I chose the .01 ohm.
Wednesday, May 4, 2011
This printer prints 3D dimensional object that is created by laying down successive layers deposited as fine as 0.007-inch of material in ABS plastic. Once design in CAD then is converted in to a stereolithography file (STL) then printed just like you would a normal paper printer, that it really that easy to use. The 3d printer is also Ethernet network capable, just set you IP and share it with you coworkers.
3D Printer Video