Social Packet Radio Operators In North Georgia

• One version, using the Meanwell RS-15-15 supply (typically $11) plugs into the wall (110 VAC) and delivers the necessary voltage. This can be purchased from many outlets, including Digikey, Mouser, eBay and Amazon.
• A second version uses the DROK 200446 buck/boost converter (typically $17) and is powered from the HP Power supply, eliminating the need for two house-current wall plugs. We've only seen this on Amazon. It is your choice whether the inconvenience of needing two things plugged into the wall outweighs the $5 extra cost.

There are less expensive options, perhaps without some features, so the key point is that it can accept at least 8 to 16 volts as input and can deliver exactly 5.2 volts (ideally adjustable, since 5.0 volts is not OK) and at least 2 Amps (11 Watts)

The Raspberry Pi, like many computers, gets angry when power is removed from it unexpectedly. This can result in a fatal coruption of the MicroSD card that serves as the Pi's 'hard disk'. Avoid removing power unexpectedly! Instead, shut down the Pi either by using the Conmtrol Panel button, or via the Pi desktop menu.

We have found the best price for these at Battery in the cloud.

You are welcome to use a different battery (the 'charger' we use ONLY supports lead-acid chemistry! Definintely NOT any Lithium-based chemistry!). Mounting it becomes your challenge.

• A full-wave diode bridge, such as the Rectron BR62 ($0.78) available from Mouser. If you select an alternative (there are many) be certain it can handle at least 4 Amps and withstand a 100 V reverse voltage as minimums - higher values are more robust.
• A power resistor in the 50 Ohm range (47-52 is fine) rated for around 10 Watts. This is used to limit the charging current to the backup battery. These can be had from many places, for example the Yageo SQP10AJB-51R ($0.65), also from Mouser

There are many other possible solutions, including a "Ground Bus Bar" of the style used in AC Power electrical panels, but these have been found to be somewhat more costly.

Recommended are the following:

• An assortment of #18 wire in different colors. Search on Amazon for B085QD9DWP ($18). Others sell similar kits, just be sure it's #18 wire and stranded copper. No need for silicone insulation, PVC is fine.
• A few feet of #18 red/black paired wires (zip cord, $8 for 25 feet). Amazon sells a LOT of this, 99% of which is copper-clad aluminum thet you definitely do NOT want. Instead try Powerwerx. They sell high quality product at very good prices.
• About a foot of #12 red/black zip cord ($25 for 25 feet). Also available from Powerwerx (see link above). Unfortunately the smallest length they sell is 25 feet. It comes in handy often, so if you can, get the whole 25 feet.
For all of these wire items, you can visit The Wireman who sells it by the foot. The different color wire assortment can be had by buying a length (maybe 8 feet? $1.45/ft) of their #302 Premium Rotor Cable, which comes with six #18 wires and two #16 wires wrapped in a single outer covering. Just remove the covering and you have eight suitable pieces of wire. Note that they often sell short end-of-reel offcuts at a discount in their clearance section - search their site for "302".

• One IEC Cord for the HP Power Supply and (if you use it) one for the Meanwell RS-15-15 Power Supply.
• A short (6", or longer) USB-C cord, to supply power to the Raspberry Pi.
• Three to Five 1/4" female crimp-on quick-disconnect contacts suitable for #18 wire
• Two 3/16" female crimp-on quick-disconnect contacts suitable for #18 wire
• One crimp-on ring terminal suitable for a #10 stud and #12 wire
• Some heat-shrink tubing in various sizes
• Velcro hook & loop tape, self-adhesive, normal strength. (The high-strength stuff can get annoyingly hard to unmate).
• Anderson PowerPole Connectors (the 15/30/45 style, with both red and black housings), or whatever connector system you prefer to use for your equipment, for #18 wire. The best prices are typically at Powerwerx (see the link in "Wire" directly above), but on occasion Impulse Electronics has a 10% off sale that is a decent bargain. Also, get a PowerPole crimper if you don't already have one: PowerPoles are the modern standard for power connections, and investing in a crimper will ensure you get good connections. Note that suitable crimpers are sold by several vendors at similar prices.
• Two minor electronic components:
  • One 330 Ohm 1/4 Watt resistor. Used to modify the HP Power Supply. These cost pennies.
  • One Littelfuse Polyfuse #30R185UU. This is a self-resetting thermal fuse that protects the wiring from a short on the battery terminals. It is rated at a 1.85 Ampere hold current, with a maximum of 30 volts. You can use a 3 or 5 Amp fuse instead, but these will not self-reset when the fault is cleared. $0.65 at Mouser.
• A couple of wood screws.
• Did I miss anything???

• The HP power supply
• The 330 Ohm 1/4 Watt resistor. This enables the power supply's voltage output.
• One foot of #12 AWG zip cord (or red and black #12 stranded copper wire, each a foot long. These instructins assume you have zip cord). This connects the power supply to the fuse box.
• A few inches of Velcro Loop tape, or thick self-adhesive felt. This insulates the (bare metal) voltage sources on the power supply.

1. Identify the soldering locations: Looking at the rear of the power supply, with the power supply top up (the six small gold contacts are on the left), note the FIRST and FOURTH small contacts. Note that the fourth contact is a bit shorter than the others. The resistor goes between these two contacts.
2. Prepare the 330 Ohm resistor by bending the wire leads to fit onto the two contacts you noted above. Cut the wire leads to about 3/8" long.
3. Tin (apply a thin later of solder to) the two contacts you noted.
4. Using the needle-nose pliers, hold the resistor in place while soldering one wire lead to one of the contacts.
5. Correct the positioning of the resistor's other wire lead if needed, then solder it to the other contact. Study the image here carefully to verify you have installed the resistor on the correct contacts.


6. Separate about 1-1/4 inches of one end of the #12 zip cord wires, and strip them about 1-1/8".
7. Twist each wire's strands together, then tin the wires heavily.
8. Tin the top gold contact areas on the power supply rear edge connector. See the image showing the tinned wires and supply contacts.
9. Using a hot soldering iron, solder the red wire to the right side (looking at the rear) contact area.
10. • Use a clip or clamp to hold the wire in place firmly against the contact surface - it will get very hot! - and be sure the bare wires won't touch each other after soldering. Take a look at the image to see how the red and black wires split apart and go to their separate sides of the power supply contact area
    • Start soldering at the tip of the wire and, while adding solder generously, move towards the unstripped area of the wire. THIS MAY GO SLOWLY, as there is a lot of heat needed and a lot of surface to heat up.
    • It can be helpful to get a large blob of melted solder on the soldering iron tip, as the mass of that blob will help transfer heat.
    • Wait for things to cool a bit, then repeat for the black wire. See the image for what you want as the end result.
    • IF YOU CAN'T get the solder to melt enough, get a more powerful soldering iron or, if you're really careful, use a soldering gun.
11. Carefully inspect the soldering work. The wires should make good contact with the power supply contact area, and the red and black sides don't touch each other. There should be solder fillets between the circuit board and both sides of the wire.
12. After you are satisfied all is well, plug in the HP power supply using an IEC cord and measure the output voltage. It should be around 12.3 Volts DC. Make sure the RED wire has the POSITIVE (+) Voltage.
13. If all is correct, cover both the top and bottom of the rear power supply connector area with velcro loop tape. You must insulate all exposed metal, since this power supply can deliver quite a lot of energy if a short-circuit were to occur.
14. Separate about 4 inches of the other end of the red/black zip cord, and strip the end of the red wire 1/4 inch. Twist the wire strands together and crimp on a ring terminal for #10 hardware.

• The full-wave diode bridge
• The 10 Watt resistor
• A few pieces of assorted-color #18 hook-up wire. (Colors may be substituted if needed, but be consistent in usage).

1. Note that the full-wave bridge consists of four diodes, arranged in a square, cathode-to-anode, with a wire coming out at each intersection. There are four wires: two "AC" wires (each using a "~" symbol), one "+" (plus) wire, and one "-" (minus) wire.
2. Identify the four wires of the full-wave bridge: First find the "+" (plus) and one of the "~" (AC) wires (marked on the device), then match these up with the image. Mark each of the terminals somehow, such as with a Sharpie marker on the bottom. If you used a part different from the recommendation, consult the manufacturer's data sheet.
3. Connect the resistor between one of the "~" (AC) lead wires and the "-" (minus) lead wire. Wrap the resistor wire leads half a turn around the full-wave bridge wires. Try to keep the resistor wire leads even in length and without any excess. Solder the resistor to the "-" (minus) wire ONLY for now.
4. Cut a 4-inch piece of orange wire and strip one end 1/2 inch. Twist the strands together and wrap the end around the "~" (AC) lead wire that is NOT connected to the resistor. Solder the wire to the bridge.
5. Cut a 4-inch piece of yellow wire and strip one end 1/2 inch. Twist the strands together and wrap the end around the "+" (plus) lead wire. Solder the wire to the bridge.
6. Cut a 3-inch piece of red wire and strip 1/2 inch from one end. Twist the strands together and wrap the end around the "~" (AC) lead wire that is also connected to the resistor. Solder the wire and resistor lead to the bridge.
7. Strip the free ends of the red, pink and orange wires 1/4 inch. On the orange wire, twist the wire strands together and crimp on a 1/4 inch crimp-on quick-disconnect terminal.

• Two 22-inch pieces of #18 hookup wire, one orange and one black.
• The Polyfuse (or other fuse device).
• One 1/4" female crimp-on quick-disconnect contact suitable for #18 wire.
• Two 3/16" female crimp-on quick-disconnect contacts suitable for #18 wire.

1. Strip both ends of both the orange and black wires to 1/4 inch.
2. To one end of the black wire, crimp one 3/16" female crimp-on quick-disconnect contact.
3. Solder to one of the Polyfuse's leads a 3/16" female quick-disconnect contact. Note that the Polyfuse wire is too small to crimp properly - it is necessary to solder the polyfuse wire lead to the contact. The images show the wire lead laying on the contact, then the contact after soldering. In the third image, note that the 'ears' of the quick-disconnect contact have been bent down over the soldered wire lead.
4. Solder one end of the orange wire to the other wire lead of the Polyfuse.
5. Slip a suitable (1/8"-3/16") piece of heat-shrink tubing over the orange wire and heat it to completely cover and insulate the solder connection to the Polyfuse. Repeat this for the other lead wire of the polyfuse with the 3/16" contact (1/4" heat shrink works well here). Since this is the positive (+) connection to the battery, take extra care to ensure that no bare metal is exposed. The fourth image shows a fully-insulated Polyfuse.
6. To the other end of the orange wire, crimp a 1/4" female crimp-on quick-disconnect contact.

You should end up with two wires, the black one that connects to the battery (-) negative terminal and to the upper Wago Lever Nut, as well as the orange wire that connects to the battery (+) positive terminal and one of the male 1/4" quick-disconnects on the back of the Control Panel.

In this step, you will assmble the power cords that are connected to your node radios. We give instructions for one, using PowerPole contacts. You may use any contact system you prefer, but our loan radios all use Powerpoles. Regardless of the connectors you use, consider making three, so you have them in the future.

For this step, you will need:

• One 12-inch piece of #18 red/black paired Zip Cord.
• Two PowerPole contacts suitable for #18 wire. (We use the 15A contacts successfully).
• One set (Red/Black) PowerPole connector bodies.
• One 1/4" female crimp-on quick-disconnect contact suitable for #18 wire.

1. Separate about an inch of one end of the Zip Cord, and strip each wire to 1/4 inch.
2. Crimp a PowerPole Contact to the red and black wires. The top image shows two good crimps: A small bit of wire showing at the end of the crimp barrel (arrow), a full crimp, and no (or almost no) copper showing on the insulation side of the barrel.
3. Insert each contact into the correct color housing.
4. Arrange the red and black housings as shown and slide them together. The black housing sides from the rear towards the front of the red housing.Getting this orientationn correct is important!
5. Strip the other end of the red wire to 1/4 inch and crimp on a 1/4" female crimp-on quick-disconnect terminal.

Repeat for as many wires as you want.

This completes the Radio Power Wire preparation.

• MEANWELL RS-15-15: Using the two M3 x 13mm machine screws, install the Meanwell RS-15-15 to the left side of the NodeBox top. The terminal screws of the Meanwell MUST be located in the area shown in the image (arrow): This allows the small Pi holding plate (not shown) to provide additional protection against accidental contact with the 110 VAC power input terminals.
  THIS IS A SAFETY ITEM, BE TOTALLY CERTAIN.
  The screws are just long enough to fit, and are installed from the inside of the NodeBox upwards through the holes provided. Use care to line up the holes properly.
• DROK 200446: Using generous strips of velcro, mount the DROK 200446 to the left side ot the NodeBox top. The output terminals should be facing the Pi Power Supply.

NOTE: Strip wires 1/4" where they are connected to a power supply, and 11mm (7/16") where connected to a Lever Nut.

To use a Wago Lever Nut, lift the orange handle upwards completely, insert the stripped wire completely, then press the lever back down. Look through the bottom to inspect wire engagement and tug on the wire to verify a good contact.

1. A 6" piece from the Meanwell (-) DC Output terminal to a Wago Lever Nut.
2. A 6" piece from the (-) DC Input side of the Pi Power Supply to the Wago Lever Nut.
3. A 12" piece from the Wago Lever Nut to a second Lever Nut placed near the HP Power Supply. (If you have some heavier stranded wire, such as #16 oe #14, use that here instead).
4. Strip the black wire from the HP Power Supply 11mm and connect it to the lower Lever Nut.
5. Strip the black wire(s) on the Radio Power Wire(s) and connect to the lower Lever Nut.
6. Connect the black Battery wire to the upper Lever Nut and to the negative (-) battery terminal.