Welcome to the N1IR Electronics Website. Totally off the cuff, one take, unrehearsed video projects for anyone interested in amateur radio, electronic design, makers, hardware hackers and science.

Get off your duff and build something!
Training the hand and mind since 1982.

Wednesday, February 23, 2011

Cheap 16 x 2 Blue LCD from China

I was browsing the EEV Blog Forum and there was a question from btipton

"I've got a few hobbyist-type projects that would be nice to have LCD displays on, but I've always been turned off by how much cost it would add. I looked on eBay today, however, and saw this $1 per display seems *really* cheap, even compared to other eBay stores - is there something I'm missing? At this price, I'd probably order 30 or so just to make sure I'd always have an LCD handy."

I had been looking for LCD for a time and decided to risk a few bucks and order them. I ordered 10 at $3.49 each, if you look down the page they stating

"As there are weight and cubage restrictions on international order, we are unable to offer you any discount or combined shipping for multiple items. All items are shipped separately. There is no local pickup service, no third party shipping carrier will be used.
Listings with shipping and handling charge: the charge covers mailing, packing, warehouse and distribution costs, not postage only."

My guess is that there trying to get around some tax or customs, but for $3.49 is a good deal compared to the $15.00 I'm currently getting them for.

It seem to have a good customer service after a couple of days I got an email back saying that the Post was shut down for Chinese New Year (DOE!) but all ten arrived in about 2 weeks. all individually wrapped see photo below.

You can see the video posted below, to see it working.

Sunday, February 20, 2011

Another crazy Idea, HF GO KIT

Something a bit different that electronic circuitry, got to use my new electric carving knife, a gift from my wife (thanks hunny, I bet you didn't think I would be using it for foam.)

EMP if anyone know about EMP survivability please comment.

Inside dimension 5.5625 H X 10.9375 W x 12.8125 D (does vary by +/- 1/16 of an inch on H & W)

Saturday, February 19, 2011

Super Simple AC Line Tester

I was browsing one of my electronics catalogs and I came across the Fluke 1AC-A1-II Volt-Alert AC Non-Contact Voltage Tester, so I bought one to try it out. Some of my student that work with AC a lot really liked it. However 25 bucks a student was kind of expensive, so I came up with this design for under $2.00.

Clarifications to schematic, forgot to add a power switch (doe!), Probe connects to clock pin 14

How it works:
The heart of this circuit is the CD4017 Decade Counter/Divider with 10 Decoded Outputs. Basically when a AC signal is in close proximity to the non contact probe the counter counts from output 0 to 9 in sequence one single output on at any given time then lights up the MAN74 Seven segment display in order from segment a,b,c,d,e,f then resets back to a producing a chase pattern. The decimal point on the MAN74 is a power on LED indication. The non contact probe is made from insulated 22AWG wire in a loop.

Additionally this circuit will also detect any clock or data line in a digital circuit. If you want to control the sensitivity you can connect a 100K potentiometer to the probe to ground, the closer the wiper is to ground the less sensitive it is.

Home QTH

My home Lab/QTH featured on The AMP HOUR workbench of the week.


The Amp Hour

Thursday, February 17, 2011

Sealed Lead Acid Battery Monitor (SLAB_M)

Greetings all, Here is another one of my projects. Sealed Lead Acid Battery Monitor (SLAB_M). Basically this is a voltage comparator circuit. I used the LT6700, thank you linear technology for the samples! In the LT6700-3 there are two non-inverting comparators, in the data sheet they used two for a high/low battery condition, I just needed one so I paralleled them. This is for two reasons, first is any noise on a open input the second is I doubled my output current capacity from 5mA to 10mA of the op-amp. Supply range is from 1.4V to 18V perfect for a SLA 12V 80AH battery. Total quiescent current measured about 20uA, about one thousand time less than the natural decay of the battery sitting with no load. Total current with the buzzer in the trip state is around 5 mA. Once the voltage drops to 10.6 volts the buzzer will sound until the voltage rises above 10.6 volts. Hysteresis measure was very small about 5 mV, in fact I had a hard time measuring this with the equipment I have at hand, the characteristics on/off was so sharp. There was an error in the video I mentioned 60mA, I didn't see the decimal point it's 6mA when simulated. I used NI Multisim 10 for the circuit simulation and traxmaker 2000 for the PCB. Gerber file are available by email. There is a high voltage version that I used (LT6700HVHS6-3#PBF) the max input is 36 Volts. The CS Version at 18 Volts was kind of cutting it close in my final application with a solar cell charger (17V no load). Go and build something! N1IR de CJ..73's

Monday, February 14, 2011

SMT work

Some stuff I'm working on in SMT. The top PCB is an ATmega328, Arduino Mini 04 clone. I basically stripped the stuff I didn't need. The regulator, caps, protection diodes all have been removed and strip down to just the 328 and a resonator and a pull up resistor for reset.

The bottom PCB is a break out for the MAX4239ASA+ Ultra-Low Offset/Drift, Low-Noise, Precision op-amp. I'm currently developing a cheap current detector for the arduino. Basically it's a current to voltage converter (0-1A input 0-5V output) in a differential amplifer configuration for the op-amp. I have a .01 Ohm 1% current sensor resistor in series with the load to detect the current. This should give me a resolution of .9mA per step with a very low burden voltage.

3 In One

3 in One is a Logic Probe / Continuity Tester / Audio Tracer. In work we got over (6000) LM324 donated to us. This is one of the projects we build. It uses one LM324 and one LM386.

How it Works: Comming soon.

Sunday, February 13, 2011

Name Badge Project

Badges...Badges...We don't need no stinking badges. Ah but maybe and electronic version! Just me farting around down in the basement lab at home. I ordered a bunch of the 16x2 LCD and Arduino Liliypads for work. Just for fun wonder what I could make in a couple of hours. I did this project the night before a class I was teaching for my amateur radio club. It was a big hit and got a lot of other people in my group interested the the Arduino. Very easy project for someone just staring out with the arduino. If I get some feedback I may produce a smaller improved version but it will probably remain in the prototype stage....one off.

Sorry for the quality of the video, I haven't found a good video editing software for Ubuntu yet, so this is all on one take, one shot.

Saturday, February 12, 2011

Adafruit TV-Be-Gone Kit

Here is the N1IR review on the tv-be-gone kit, tune in to this site for my design changes. Enjoy.

NBEMS Cable interface

NBEMS is Narrow Band Emergency Message System. Think back to your last public service event, drill, or deployment. You probably passed a lot of traffic best suited for voice communications but...What if you had been asked to pass Roster of evacuees, Required prescription medications, Directions to a disaster scene. The needs of our Served Agencies have changed. They still need voice communications but...There's an increasing need for data communications. We need to be able to provide more than just voice communications from a ham with an HT. *1*

As seen in June 2009's QST Howard “Skip” Teller, KH6TY "A Sound Card Interface for FM Transceivers". There are a couple of differences with my design, my version will work with isolated microphone ground common on HF radios. And my sound card plug is integrated with the unit so you don't loose it. Software to use NBEMS is at www.w1hkj.com/NBEMS/

How does it work? When you have sound out on your sound card the audio goes through a audio transformer for isolation and impedance matching to the microphone input of the radio. Next the audio gets amplified though Q1, after Q1 the audio goes though a bypass cap C3 and get rectified via D1/D2 and charges C4. C4 value changes the PTT hang time with a 10uF it's approximately 2 second after the audio stops. When C4 reaches .7 volts or more Q2 turns on and conducts PTT line to ground. See below for schematic.

I've made a small production run of two versions, one version uses a common ground for the PTT and microphone, used with most Yaesu 2 Meter radios. The second version has two addition 1uF caps that isolate the mic ground from the PTT ground used with most Kenwood 2 Meter radios.

These projects where sold for charity to the Genesis Amateur Radio Club Repeater Fund. Please e-mail me if you would like the Gerber files for this project.

Tools I used for this project:
T-Tech PCB Milling Machine QC5000
Traxmaker 2000
Soldering Iron
Milling machine

Citations of other works
1. www.portal.state.pa.us/...pt/.../nbems_presentation_power_point_pdf


N1IR Electronics Blog

Hello my name is Chris Johnson and this page is set-up to display some of my electronic projects. All projects are open source / open hardware please share them. Information on this site is for anyone interested in electronics, electronics designs and makers alike. And remember "one person, one hobbyist, one hacker, one maker......can change the world!" Dave Jones EEVBLOG