Wednesday, February 26, 2014

Smallest DIY "Stripboard" Arduino design I have seen

Instructables has this little how-to for the YABBAS -Yet Another Bare Bones Arduino design


Easy, cheap and very nice.

Use Server PSU for your HAM radio

The user "xandrios" on RCgroups.com has composed this briliant how-to on getting a server-psu to be used outside the datacenter ;-)

5vsb -  The sb stands for standby. It means that the 5v will be available in all modes of operation. Powered up, powered down(standby) and during a fault condition.
Bringing that up, this is the method I used to find the correct pins to power up this supply. It also works for a majority of PS units out there.

With power off and testing each pin to ground.

1. Exclude any pins that are common to each other(including ground pins). Usually these are the 3v and 5v rail pins. They also show the same resistance.

2. Exclude any open pins(pins with no resistance that don't connect to anything).

3. Exclude any pins with a value below 1k ohms and above 10k ohms. From my experience, I've found that the pson and pskill resistance usually falls between a 1k and 10k range.

With power on.

4. Exclude any pins that show no voltage.(pson and pskill are held partially TTL high or just not grounded. So they show some voltage on them).

This will usually leave between 4-6 pins.

Use a .5k ohm resistor on each of the individual remaining pins and connect each to ground. The power supply will usually power up at this point.

Disconnect one resistor at a time from ground.

If the PS remains on after a you disconnect a resistor from ground, then the remaining pins contain the pson and pskill. So keep it disconnected from ground.

If the power supply turns off, then the disconnected pin is either the pson or pskill. So reconnect it to ground.

Repeat this process until you find the pson and pskill pins.

In some cases the PS will turn on with a fault.

If this happens then disconnect one resistor(pin) at a time from ground to find the one that is causing the fault. Then continue with the process above to find the pskill and pson pins.


All above is from: RCgroups.com