The Ultimate Prototyper's Varible Output Power Supply PART NO. 2177900

Do you need a variable power supply but don't have the space or budget for the expensive benchtop models? The Ultimate Prototyper's Variable Output Power Supply will provide up to 1.5A of regulated DC current at any voltage between 1.2V to your input voltage (max 12V). Use for field testing of an analog amplifier or just to see how bright that LED shines.

Warning: Due to the bare electrical connections on the power supply, do not use the power supply on a conductive surface or near conductive objects such as metal tools. For protection, it is advised that you cover the assembly in electrical or duct tape to prevent shorts that may cause batteries to overheat. If you notice any component becoming very hot or smoke, remove the batteries immediately and turn the power supply off.

Time Required: 20 minutes depending on experience Experience Level: Beginner Required tools and parts:

Soldering Iron and Solder Pliers with wire cutters 3d hand or clamping device Small flat head screwdriver Superglue, epoxy, or other permanent adhesive

For 9V input, use a standard 9V battery. For 12V input, use Jameco part 216267 or 216259 For 6V input, use Jameco part 2128083.

Bill of Materials:

Qty Jameco SKU Component Name 1 23579 LM317 1.2-37V 1.5A regulator

10 29831 1uF electrolytic capacitor

10 609545 0.1uF electrolytic capacitor

1 255514 5K ohm potentiometer 10 2160964 470 ohm resistor 1 76523 SPST Switch

1 11280 9V battery clip 1 159863 Bananna Plug 1 2152905 Red Wire Cut two 3" segments from the roll 1 2152876 Black Wire Cut one 6" segment from the roll 1 102788 Knob

Step 1 - Schematic

This schematic shows all pin connections so you can verify your work. Components may appear slightly different than those shown inthe schematic, but pin assignments are identical.

Step 2 - Install LM317

First, bend pin 1 of the LM317 such that it slides through the middle solder eyelet of the potentiometer. Bend the end of the pin up so that it forms a hook through eyelet of the potentiometer. Second, put a very tiny amount of glue onto the back of the transistor and press it against the back of the potentiometer. Hold in place for 1 minute. Third, wrap one of the leads of the 470 ohm resistor through the center and right solder eyelets of the potentiometer, shorting the two eyelets. Finally, solder these two eyelets. Step 3 - Connect components to ground

Twist the negative leads of both capacitors together and thread them through the remaining eyelet of the potentiometer. Next, strip 1/2" of insulation from one end of the 6" black wire and black wire on the 9V connector. Twist these wires and feed through the eyelet on the potentiometer. In the picture, you can see from top to bottom: 0.1uF capacitor with positive lead bent, twisted black and 9V- leads, 1uF capacitor with positive lead bent. If there is no space in the eyelet, twist the wire or lead around the stem of the eyelet. Finally, solder this eyelet.

Step 4 - Solder output node

First, bend the LM317 lead downwards in half to form an eyelet. Next, strip 1/2" of one previously cut 6" red wire and wrap the end around the eyelet. You may need to add some solder to hold the wire in place. Then bend the free lead of the resistor and positive lead of the 1uF capacitor so that they touch the LM317 pin 2 but are away from any other metallic surfaces. If necessary, use electrical tape to insulate bare portions of the leads. Finally, solder the joint containing pin 2 of the LM317, the red output wire, resistor, and positive lead of the 1uF capacitor. Step 5 - Install switch

Put the 9V+ red wire from the 9V connector into one of the solder eyelets on the switch. Strip 1/4" of the second 6" red wire and put it in the other solder eyelet on the switch. Solder both eyelets to secure the switch connections. Use heat shrink or electrical tape to insulate the connections.

Step 6 - Solder input node

Bend pin 3 of the LM317 in half upwards to create an eyelet. Loop the positive lead of the 0.1uF capacitor through this eyelet. Also loop the stripped end of the new length of red wire (soldered to the switch in the previous step) through the eyelet (wire connected to switch). Finally, solder the input node.

Step 7 - Add Banana Plug to output leads

Strip the output wires and insert them into the red and black Banana plugs as shown. You may need to loosen the setscrew before inserting the wire. Once the stripped end of the wire is fully inside the connector, tighten the setscrew. Add the knob to the shaft of the potentiometer. Your Power Supply is now complete!