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hardware:autopoweron 2009/08/31 04:20 hardware:autopoweron 2017/09/06 18:38 current
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==== For older DNS-323 hardware versions ==== ==== For older DNS-323 hardware versions ====
-The above circuit works for hardware version B1, which has a power switch that grounds an input line. Older version may have a power switch that pulls a line up on closure instead.  Skydreamer provided a revision of the above circuit for the older hardware versions. +The above circuit works for hardware version B1, which has a power switch that grounds an input line. Older versions of the DNS-323 hardware may have a power switch that pulls a line up on closure instead.  Skydreamer provided a revision of the above circuit for the older hardware versions. 
-Skydreamer's note- for older hardware revisions: This auto power on circuit needs to be modified for older hardware revisions that drive the switch from +12V instead of 0V. You will need one resistor 47 kOhm and one PNP signal transistor (such as BC560). Connect NE556 pin#9 over the 47 kOhm resistor (anywhere from 10K to 50K should work fine) to the base of the PNP transistor. The emitter is connected to the side of the switch marked with the black grounding symbol (not the grounding shield!), the collector to the opposite one with the yellow wire attached on the picture. Do not connect pin#13 to the switch- leave out the yellow wire. Power the circuit from +12V and not +5V as advised below.  That is, modify the above circuit to take power from 12V and to feed its pin 9 output to a PNP transistor placed directly across the DNS-323 switch, as shown in the following schematic: + 
-{{ hardware:circuit-for-old-hardware.png |}}+Skydreamer's note for older hardware revisions: This auto power on circuit needs to be modified for older hardware revisions that drive the switch from +12V instead of 0V. You will need one resistor 47 kOhm and one PNP signal transistor (such as BC560). Connect NE556 pin#9 over the 47 kOhm resistor (anywhere from 10K to 50K should work fine) to the base of the PNP transistor. The emitter is connected to the side of the switch marked with the black grounding symbol (not the grounding shield!), the collector to the opposite one with the yellow wire attached on the picture. Do not connect pin#13 to the switch- leave out the yellow wire. Power the circuit from +12V and not +5V as advised below.  That is, modify the above circuit to take power from 12V and to feed its pin 9 output to a PNP transistor placed directly across the DNS-323 switch, as shown in the following schematic: 
 +{{ hardware:circuit_for_old_hardware.png |}}
===== Circuit operation ===== ===== Circuit operation =====
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If you are successful, whenever the power is plugged in the DNS-323 should automatically turn on after about ten seconds. If you are successful, whenever the power is plugged in the DNS-323 should automatically turn on after about ten seconds.
 +~~CLEARFLOAT~~
 +===== Other solutions =====
 +There is also another auto turn on circuit available, [[http://www.waggies.net/Ken/dns323/index.htm |this one using a hex inverter]].
 +====== Single capacitor solution (B1 hardware) ======
 +**Background info:** The power on button is connected to pin 1 of HT48R05A-1 (U25) and has a weak 120k pull up.  The H48R05A-1 is an 8 bit micro-controller from Holtek which conveniently handles very slow rise time inputs. 
 +
 +**Solution:** With such a weak pull up value, all you need is a (fairly large) capacitor to delay the rise time, which tricks the HT48R05A-1 in thinking the power button has just been released.
 +
 +
 +===== How to do the mod =====
 +
 +  - Disassemble your DNS-323 (4 screws on the front, 4 screws in the back, another set of 4 screws in the back, and you're done).
 +  - {{  hardware:power_on_switch_bottom.jpg?300|}} Solder a 150uF (6.3V or higher) electrolytic capacitor between the ground (circled in black) and the power on pin (circled in red). 
 +    * **__NOTE: electrolytic capacitors are polarized!!!__**
 +    * Make sure the negative is soldered to ground (the side of the capacitor will have a large stripe next to the pin).
 +    * About the capacitor... I am pretty sure a lower value (ex.: 68uF) will also work, but I didn't try.  I have a feeling high ESR capacitors are better since a 15uF __unpolarized__ capacitor (used for AC relays) worked fine yet it's 15 uF electrolytic equivalent didn't.
 +  - Reassemble your DNS-323 and enjoy. 
 +
 +**Note:** The power switch still works to power off the unit, and to power it back on if it was powered down by the switch or by software shutdown.\\
 +
 +\\ **Limitations**
 +  * Doesn't work for power glitches (anything below 3-4 seconds). 
 +    * {{  hardware:power_on_optional_diode.jpg?300|}}**To fix this limitation**, you can put (in theory since I didn't try it) a diode in parallel to the weak pull up (R209, which is near U25).  When the 5V rail fails, the capacitor should discharge very quickly.  The N side of the diode should be near the "R" of "R209".
 +    * If you are serious about your NAS, it should be on a UPS (which filter glitches) and therefore you don't need to add a diode...
 +
 +~~CLEARFLOAT~~
 +**Assembly pictures**\\
 +I stole an electrolytic capacitor from a unused electronic circuit.  The leads weren't long enough, so I had to use wire.  The electrolytic capacitor you'll buy will likely have leads long enough so you won't need to go through this hassle. (But make sure that non-isolated leads don't touch front panel after assembly. The panel is actually made of (anodized) aluminum and there can easily be a short-circuit, leading to router powering down soon after start up - or worse.)
 +\\ {{hardware:power_on_capacitor.jpg?300|}} {{hardware:power_on_final_result.jpg?500|}}
 +~~CLEARFLOAT~~

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