Category: Amateur Radio

Using and building radio gadgetry

Amateur Radio, Electronics Workbench, Home Ec, Science

Garage Opener Antenna Director

By a quirk of fate, the Chamberlain garage door opener in our new house has the same “purple learn button” as the Sears opener in our old house, so I introduced it to our remotes and they work just fine.

I then replaced the four-button remote in my bike pack with a new single-button remote to reduce the dexterity required to hit the button:

Garage Opener - one button
Garage Opener – one button

Alas, the opener only responded when the remote was immediately outside the aluminum garage door. Checking the battery (because sometimes “new” does not mean what you think it means) reminded me we live in an age when hardware is free compared with bookkeeping:

Garage Opener - interior
Garage Opener – interior

Maybe the second button doesn’t work and this is how they monetize their QC reject pile?

I want the door to start moving when I’m at the end of the driveway, giving it enough time to get all the way up so I can bike right in. You can actually buy remote / extension antennas, although for fancier openers with SMA antenna connectors, but sometimes a little RF black magic will suffice:

Garage Opener - crude antenna director
Garage Opener – crude antenna director

The wavy wire hanging down from the opener’s rear panel is the original antenna, which might be kinda-sorta omnidirectional. The opener operates around 433 MHz= 69 cm, so a quarter-wave antenna will be 17 cm = 7 inch long; the (unbent) wire is maybe 10 inches long from the hole in the panel.

So I taped 11 inches of wire to the opener to form a very very crude Yagi-Uda antenna. It’s too long to be a director element, it’s about right (albeit in the wrong place) to be a reflector element, it might be neither.

What it does do is warp the antenna’s pattern just enough to let the remote reliably trigger the opener as I approach the end of the driveway.

Do not even begin to think about polarization mismatch from what looks like the tiny loop antenna on the remote’s PCB.

Amateur Radio, Machine Shop, Recumbent Bicycling

Tour Easy: DPC-18 Display Controls

The Bafang 500C display I installed on Mary’s Tour Easy recumbent has assist level buttons along its left edge:

Bafang display - clamp bushing
Bafang display – clamp bushing

This required her to take her left hand off the handlebar to fiddle with the assist level and, as it turned out, used her thumb in position causing some distress. Given that changing the assist level happens a lot as we ride, it was time for a change.

So I replaced the 500C with a DPC-18 display like the one on my bike, with the key advantage of putting the buttons on the handgrip:

Tour Easy Bafang Controls - DPC-18 buttons
Tour Easy Bafang Controls – DPC-18 buttons

She preferred a higher position for the buttons than I do, with the PTT button for the Baofeng amateur radio below the housing.

After a few iterations, the throttle moved from the right handgrip to the right end of the handlebar crosspiece on a lengthened version of the mount I conjured for Tee’s Terry Symmetry upright bike:

Tour Easy Bafang DPC-18 - throttle mount
Tour Easy Bafang DPC-18 – throttle mount

That location requires a bit of dexterity, but let us move the twist-grip shifter upward on the handgrip where it is more comfortable. She rarely uses the throttle, so we’ll try this for a while.

The DPC-18 has an awkward portrait-mode display with an incredible amount of wasted space, with the side detriment of displacing the blue Camelbak hose. After a few iterations, we settled on a receptacle to catch the mouthpiece without requiring any fancy snaps / clips / fasteners:

Tour Easy Bafang Controls - Camelbak nozzle catcher
Tour Easy Bafang Controls – Camelbak nozzle catcher

The solid model descends from the Zzipper fairing mounts on that same aluminum bar, with the bottle simply jammed into the big hole:

Zzipper Fairing - Camelbak nozzle catcher - show layout
Zzipper Fairing – Camelbak nozzle catcher – show layout

There being no real forces on the holder, I omitted the aluminum load-spreading plate across the top and just epoxied four threaded brass inserts into the bottom part.

Early reports suggest a happier thumb and no problems stashing the hose, so it’s all good.

Administrivia, Amateur Radio, Electronics Workbench, Home Ec, Oddities

Christmas Bonus

An email arrived yesterday:

Subject: [redacted] review blog invitation about bluetooth programmer

Message: Hi dear,

Thanks for taking time to read this email.

I am Colleen from [redacted] brand, we sell two way radio on Amazon. I learned that you have wrote two way radio review blog before and I think your blog was written well.

Now we have a product named bluetooth programmer that need to be reviewed. […] We would like to invite you to write a review blog about it.

Your can earn $2 from each product sold! We promise it. Just put the link we provided you in your blog and the Amazon backstage will count the data. And we will pay you $2 for per product sold by your link through PayPal on the 30th of every month. (Please provide your PayPal account)

If you are willing to help us write a blog, please tell us if you have a radio and your address we will send you the product for free to review.

You can view more detailed information through this link:

[redacted]

Perhaps this “review” caught their eye:

Baofeng UV-5RE radio - overview
Baofeng UV-5RE radio – overview

Or maybe it was my opinion of the Baofeng intermod problem?

Most likely, it’s just the result of an ordinary web search.

You might think everybody would know about Amazon’s crackdown on out-of-band review kickback scams, but either word hasn’t gotten around or the rewards still exceed the penalties. I think the latter applies, particularly when the offender (or its parent company) can spin up another randomly named Amazon seller with no loss of continuity.

“Earning” two bucks on a few purchases during the course of a year won’t move my Quality of Life needle, so I reported them to Amazon and that might be that.

For future reference, the chat with Amazon’s Customer Support rep produced a deep-ish link to their otherwise un-discoverable “Report Something Suspicious” page; the randomly named nodeld is a nice touch.

Speaking of randomly named sellers, it’s highly likely any Brand Name you remember from the Good Old Days has been disconnected from the tool / hardware / service you remember. Perusing a snapshot of the who-owns-who tool landscape as of a few years ago may be edifying: I didn’t know Fluke and Tektronix now have the same corporate parent.

Enjoy unwrapping your presents and playing with your toys …

Amateur Radio, Electronics Workbench, Recumbent Bicycling

Bafang Headlight Circuit Current Limit

Having just replaced Rev 1 of the amber running light with Rev 3 (about which, more later) on Mary’s Tour Easy, both the front and rear lights began blinking erratically. Given that they have completely independent circuitry, this strongly suggests a power problem.

Herewith, the headlight circuit voltage:

Bafang headlight voltage - two 1 W running lights
Bafang headlight voltage – two 1 W running lights

The voltage should be a constant 6 or 6.3 V, depending on which description you most recently read. That is the case with only one light attached, so the problem occurs only when running both lights.

The four pulses come from the amber LED’s Morse code “b” (dah-dit-dit-dit) with a 85 ms dits; the first dah pulse should be three times longer than the dits and definitely isn’t. The rear light’s red LED stays on continuously, except for two dark dits, so it draws a constant current and does not produce any changes in this trace.

Both lights have 2.0 Ω sense resistors setting the LED current to 400 mA, which corresponds to 250 mA each from the Bafang controller’s 6.3 V headlight circuit. The headlight circuit’s total of 500 mA should work fine, although the “spec” seems to be basically whatever the OEM headlight requires.

The Rev 1 amber light ran the LED at 360 mA with a supply current around 450 mA. That light and the rear light on the back ran fine, so the supply seems to have a hard maximum current limit at (a bit less than?) 500 mA.

The least-awful solution seems to be backing off both LED currents to 360 mA to keep the total supply current well under 500 mA.

Amateur Radio, Electronics Workbench, Machine Shop, Recumbent Bicycling

Tour Easy 1 W Amber Running Light: Firmware

Rather than conjure a domain specific language to blink an LED, it’s easier to use Morse code:

Herewith, Arduino source code using Mark Fickett’s Morse library to blink an amber running light:

// Tour Easy Running Light
// Ed Nisley - KE4ZNU
// September 2021

#include <morse.h>

#define PIN_OUTPUT	13

LEDMorseSender Morser(PIN_OUTPUT,(float)10.0);

void setup()
{
	Morser.setup();

    Morser.setMessage(String("qst de ke4znu "));
    Morser.sendBlocking();

//    Morser.setWPM((float)3.0);
    Morser.setSpeed(50);
	Morser.setMessage(String("s   "));
}

void loop()
{
	if (!Morser.continueSending())
		Morser.startSending();

}

Bonus: a trivially easy ID string.

A dit time of 50 ms produces a brief flash that’s probably about as fast as it can be, given that the regulator must ramp the LED current up from zero after its Enable input goes high. In round numbers, a 50ms dit corresponds to 24 WPM Morse.

Each of the three blanks after the “s” produces a seven element word space to keep the blinks from running together.

Sending “b ” (two blanks) with a 75 ms dit time may be more noticeable. You should tune for maximum conspicuity on your rides.

1 W Amber Running Light - installed front
1 W Amber Running Light – installed front

On our first ride, Mary got a friendly wave from a motorcyclist, an approving toot from a driver, and several “you go first” gestures at intersections.

Works for us …

Amateur Radio, Machine Shop, Recumbent Bicycling

Tour Easy: Asymmetric Handlebar Grips

Installing the Bafang BBS02 motor on Mary’s Tour Easy replaced the triple chainring, so I removed the front derailleur and SRAM grip shifter. This produced enough room for the thumb throttle and a full-length handgrip on the left side:

Tour Easy grips - left installed
Tour Easy grips – left installed

The round button is the PTT switch for the HT.

The right handlebar still has the rear shifter, so it requires a shorter grip:

Tour Easy grips - right installed
Tour Easy grips – right installed

Although it may be possible to buy such a grip and, thereby, get a backup pair of mismatched grips, it seemed easier straightforward to just shorten the grip to the correct length and be done with it.

Saw off a convenient length of aluminum rod:

Tour Easy grips - mandrel sawing
Tour Easy grips – mandrel sawing

Although I actually used a steady rest to produce this, it happened during a remote Squidwrench meeting and I have no proof:

Tour Easy grips - lathe mandrel
Tour Easy grips – lathe mandrel

The 22.2 mm = 7/8 inch end matches the more-or-less standard handlebar diameter, so the grip clamp can get a good hold:

Tour Easy grips - right peeled
Tour Easy grips – right peeled

A live center supports the right end of the grip.

The red coating seems to be gooey silicone rubber molded atop a PVC tube. Rather than (try to) use a lathe bit to cut through the silicone, I cut two slits with a utility knife and the spindle turning slowly in reverse, then peeled off the rubber between the slits.

With the silicone out of the way, an ordinary cutoff tool made short work of the PVC:

Tour Easy grips - right trimming
Tour Easy grips – right trimming

That was a cleanup pass with the utility knife, as the cutoff tool left a slight flange around part of the circumference. If I had the courage of my convictions, I could probably have cut the PVC with the knife.

Chamfer the end of the cut, slide it on the handlebar, tighten the clamp, and it’s all good.

The alert reader will note the clamp should go on first, but that would produce an inconvenient lump against the right shifter. Sliding them on backwards puts the clamp at the end of the handlebar and works out better in this admittedly unusual situation.

Amateur Radio, Electronics Workbench, Home Ec, Oddities

Craftsman Garage Door Opener: Rogue Remote

Just before midnight, the garage door opened, but, being early-to-bed folks, it wasn’t either of us. I pulled my fingernails out of the ceiling, padded out to the garage, verified there was nobody (not even a critter more substantial than a spider) inside, closed the door with the hardwired control button on the wall, and went back to bed. An hour later, the door opened again, then tried to take a bite out of me when I walked under it.

I pulled the opener’s plug, yanked its emergency release latch, lowered the door, and returned to bed; it was not a restful night.

The key to the diagnosis came from the little yellow LED on the back of the opener, just above the purple LEARN button:

Craftsman Garage Opener - indicator LED
Craftsman Garage Opener – indicator LED

In addition to indicating various programming states, it also lights when the opener’s radio receives a transmission from one of the remote controls. The LED was flickering continuously, showing that something was hosing the receiver with RF.

We have three remotes: one in the car, one on my bike, and one in the back room overlooking the garage. None of them worked reliably, suggesting the RF interference was clobbering their transmissions.

Disabling the remotes by removing their batteries (which were all good) also stopped the interference. Reinstalling the batteries one-by-one identified the rogue opener:

Craftsman Garage Opener - remote innards
Craftsman Garage Opener – remote innards

The slip of paper let me isolate the battery terminal and stick a milliammeter in the circuit, which showed the remote was drawing about 1.5 mA continuously. I thought one of the pushbutton switches had gone flaky, but swapping an unused one for the main door switch had no effect.

I lost track of which remote it was, but it lived in the car or the back room for all its life, so it hasn’t suffered extreme environmental stress. I have no idea why it would fail late one night, although I admit to not monitoring the LED on a regular basis. For whatever it’s worth, in the weeks leading up to the failure, activating the opener sometimes required two pokes at the remote, but nothing bad enough to prompt any further investigation.

A new cheap knockoff remote arrived in few days and it’s all good.

Protip: different openers, even from the same company, use different RF frequencies. For Craftsman openers, the color of the LEARN button is the key to the frequency; purple = 139.53753 MHz.