The first thing we decided to do was to perform a little clutter management. All of the horizontal surfaces had become parking places for various tools and detritus. We needed to reclaim some workspace and create a safe work environment.
During the cleanup we discovered a long-forgotten kit in a polybag. It was a vintage electronic lock kit perhaps from the 80's that we had purchased for a couple of dollars via eBay. The kit was rather basic having only a schematic, a bag of parts, and PCB without any markings. No step-by-step instructions were provided. A little mystery to add to the fun!
The purpose of the device once built is to activate a double-pole-single-throw switching relay when the user enters the correct sequence of four push buttons. A reset button returns the relay to its normal setting. The kit requires a 12v input.
We had a spare unused enclosure on the shelf that looked like it would fit the kit perfectly.
|NJ2X Electronic Lock - Finished Build|
Step 1: Review all the components and determine the target location on the PCB.
- This went fairly well. The only tricky part was to make sure the orientation of the transistor, capacitor, and IC's was correct. The schematic helped.
- Some of the jumpers needed to located underneath components. This little insight helped us keep the build looking nice and neat.
- Pay careful attention to the IC's. There were three IC's with the same number of pins though 2 different part numbers. An easy mistake would have been to misplace the IC's.
- We used a generous amount of flux on the parts and board due to obvious oxidization and a little corrosion. The flux helped greatly with cleaning and promoting good soldering.
- Using cotton swabs and alcohol quickly cleaned the PCB and components of flux residue.
- This step keeps the build looking nice and neat.
- We used a drill press and 5/8 inch drill bit to prepare the faceplate.
- We used Anderson PowerPole connectors (of course) for the 12v power input with a bit of shrink tubing for added strain relief.
- We added three wires to the relay switch. These can be used for switching applications.
- We used heavier gage wire than what the kit was drilled for. This was quickly remedied with a Dremel tool and suitable bit.
- Test 1: Activate the relay (no load) by entering the correct lock sequence. SUCCESS
- Test 2: The relay is not activated (no load) by entering an incorrect lock sequence. SUCCESS
- Test 3: Add a load (audio continuity tester) to the switch inputs and repeat tests #1 and #2. SUCCESS
- Test 4: Repeat tests #3 using the other pole of the relay. SUCCESS
On the application side, we still haven't decided what we need to turn on or off with this device yet. You never know when inspiration will strike. When it does, we will put this device to good use.
Good DX and 73, NJ2X
Other project articles on NJ2X.COM:
- Solder Smoke Night March 2013
- Project: PicoKeyer Plus Kit
- Project: PAiA P60 Regulated Power Supply Kit
- Project: Anderson PowerPole Polarity Checker
- Project: Morton Salt Box Crystal Radio Repair (Part 1)
- Considerations For A New Antenna - Part 2
- Project: Home Brew 9 Volt Battery Clip
- Project: Anderson Powerpole to 2.1mm Connector Pigtail
- Project: Car Power Adapter to Anderson Powerpole
© Michael W. Maher and NJ2X.COM, 2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Michael W. Maher and NJ2X.COM with appropriate and specific direction to the original content.