Arduino controlled Useless box

Recently I purchased a "useless box". You turn on a switch and an arm immedietly pops out and turns the switch back off again. It was a bit boring so I bought an L298N DC motor controller and use an Arduino Nano. The motor controller is an H bridge which can switch the polarity going to the motor. I didn't bother with the protection diodes and so far it hasn't died.

It's built on strip board.

Here's how it behaves with a random delay.

The code has to read the main switch and a limit switch which is closed when the arm is "home" inside the box. I implemented the logic as a little state machine. To get a random number on an Arduino for the delay, an unterminated A/D pin is read to provide the random seed.

Here's the final form boxed up. I power it from a USB power bank. Amazingly the Arduino is able to power the motor just fine.

I tried to vary the speed of the motor by driving it with pulse width modulation but this motor doesn't seem to vary with PWM.

My head hurt writing the code for the required logic until I rememberd the state machine. This is the way.

// Switch connections

const int kMainSwitch = 2;

const int kLimitSwitch = 4;

// Motor A connections

const int kIn1 = 8;

const int kIn2 = 7;

// switches are pulled LOW when on

int gMainSwitchValue = HIGH;

int gLimitSwitchValue = HIGH;

// on the first go, don't delay

int gFirstGo = true;

enum State {

eStopped,

eForward,

eBackward

};

enum State state = eStopped;

void setup() {

pinMode(LED_BUILTIN, OUTPUT);

// Set switch inputs

pinMode(kMainSwitch, INPUT_PULLUP);

pinMode(kLimitSwitch, INPUT_PULLUP);

// Set the motor control pins to outputs

pinMode(kIn1, OUTPUT);

pinMode(kIn2, OUTPUT);

// Turn off motors - Initial state

digitalWrite(kIn1, LOW);

digitalWrite(kIn2, LOW);

// read an unterminated analog pin for the random seed

randomSeed(analogRead(0));

}

void loop() {

gMainSwitchValue = digitalRead(kMainSwitch);

gLimitSwitchValue = digitalRead(kLimitSwitch);

switch(state) {

case eStopped:

stop();

if(gMainSwitchValue == LOW) {

state = eForward;

if(gFirstGo == true) {

gFirstGo = false;

} else {

delayRandom();

}

}

break;

case eForward:

forward();

if(gMainSwitchValue == HIGH) {

state = eBackward;

}

break;

case eBackward:

backward();

if(gLimitSwitchValue == LOW) {

state = eStopped;

}

break;

}

}

void delayRandom() {

int seconds = random(5);

delay(seconds * 1000);

}

void forward() {

digitalWrite(kIn1, HIGH);

// Tried slow motor with PWM but doesn't have much effect

//analogWrite(kIn1, 120); // 0 - 255 PWM

digitalWrite(kIn2, LOW);

}

void backward() {

digitalWrite(kIn1, LOW);

digitalWrite(kIn2, HIGH);

}

void stop() {

digitalWrite(kIn1, LOW);

digitalWrite(kIn2, LOW);

}

FreeDV Sunday net - 18 Stations

Another active FreeDV RADEV1 net in South Eastern Australia this morning on 7.177Mhz. Some stations were not in a position to transmit but I've counted them all. VK2DUX, VK3BRT, VK3CKY, VK3KQT, VK3SRC, VK4WGR, VK5KVA, VK5LN, VK6KR, VK6POP, VK3KEZ, VK2TLQ, VK5JSA, VK3JF, VK3YV (Portable!), ZL2TJM.

Improved my 40m dipole using a DJI Neo drone

I'm lucky to have lots of space and some nice tall trees. In the past I've raised antennas with a squid pole,  thrown weights and drones but my new drone, the DJI Neo has propeller guards which avoids the string getting tangled in the prop. Here I show how high I've got my 40m dipole.

Web GUI for the QRPLabs QMX

An interesting project spotted on the QRPLabs group by Paul DJ0CU/G4ADF. It's a pure web page app that connects to a QMX via USB and lets you control it. Also supported is audio streaming and it draws a little spectrum display. https://github.com/Sparks72/QMX-new-GUI Very clever! 

It uses serial from the web browser for control and captures the USB audio device.

Guest appearance on ABC Download This Show

The Australian Finance Industry Association has modelled AI's contribution to economic growth in the years ahead. It found that "scaling", or expanding, the use of AI could add up to $60 billion to GDP over the next decade. But who is actually going to benefit from this, and where are we getting these numbers from?

Also, we explain the blossoming $100 billion bromance between Nvidia and OpenAI, and how Gen Z elected their new PM via the gaming app Discord amidst a wave of protests.

Plus, the latest on the teen social media ban.

GUESTS: 

Mark Serrels, Editorial Director at CHOICE

Peter Marks, software developer at Access Informatics

This episode of Download This Show was made on Gadigal land.

Technical production by Craig Tilmouth and John Jacobs. 

Listen here: https://www.abc.net.au/listen/programs/downloadthisshow/ai-boosts-economy-nvidia-openai-investment-nepalese-election/105764962 

Notes on my weird audio. I was remote and they couldn't get the normal iPDTL audio stuff to work so we connected using FaceTime Audio. Additionally, I've started using a RODECaster Duo and I had enabled the Aphex effects including the "Aural Exciter". It certainly makes me sound more punchy and nicely suppresses my microphone popping but on listening back I think I'll dial it back in future.

Tech Talk on ABC Radio - Mobile Phones

Tech Stuff - With the Optus outage over the weekend leading to the deaths of multiple people, it showed the network and technology we now rely on to survive is not infallible. But how did we get to this point? Nightlife takes a look at the past, present and future of mobile phones and their place in our lives. 

Peter Marks, mobile software developer and technology commentator from Access Informatics joined Philip Clark and listeners to Nightlife with a comprehensive discussion. https://www.abc.net.au/listen/programs/nightlife/nightlife/105786510  

FreeDV Sunday net 10:30 eastern time 19 stations

Another well attended Sunday morning net. Seen were VK3AWA, VK3KEZ, VK3SRC, VK3YV, VK5KVA, VK3PCC, VK2KNC, VK6KR, VK3AMO, VK3BRT, VK3SPX, VK7DIK, VK5APR, VK4WGR, VK5IS, VK2TTL, VK2BLQ.

FreeDV reporter was experiencing some issues but I decided to work from a list in my log book which saved my bacon.

Thanks to all those who tuned in.

Peter, VK5APR, (a net regular) has sent the following useful links for new users:

FreeDV User Manual, which is very comprehensive

Ham friendly introduction to the concepts of RADE:

https://github.com/drowe67/radae/blob/main/doc/rade_intro_waveform.pdf accessed from https://freedv.org/davids-oct-2024-update-real-time-rade-bbfm/ 

Davids presentation to the AREG ( areg.org.au ), a local amateur radio club in Adelaide, March 2025 meeting:

https://youtu.be/LxjcAF7Vy0Y accessed from https://freedv.org/rade-ham-club-presentation/ on the FreeDV blog dated March 22, 2025

For the technically inclined:

https://arxiv.org/abs/2505.06671 accessed from https://freedv.org/david-july-2025-waspaa-paper-papr-rade-v2-snr-bbfm-otc-demo/

As always the main site is https://freedv.org/ and also keep an eye on the blog posts.

Enjoyed the Radio Old Timers Club lunch in Melbourne

Always a pleasure to attend these lunches. An efficient annual general meeting (I've joined the committee). Lovely to catch up with many old friends.

The multi-talented VK3YE was on tonight's ABC TV news

Watching the local TV news tonight and was pleasantly surprised to see a familiar face, home brew hero, Peter, VK3YE:

Seeing him described as "Bus Expert" leaves too much unsaid. Here's my touched-up version:

The story showed a chart of expendature on buses by each state with Victoria coming last.

I'm told that VK3YE was also active on 774kHz AM in the morning running very high power.

Great stuff Peter.

 

Morning walk in the Australian bush with a DJI Neo drone

Almost every morning I go for a walk in the state forest opposite my house. It's very peaceful. This week, I purchased a little drone for antenna hanging activities and it turns out to have a "follow" mode where it will fly along behind you recording video. 

Here's another walk, and a bit of a jog!

Later in the day I got my 40m dipole suspended higher in the trees. I tied flourescent bricklayer's string around the drone and flew it right over a near by tree and used it to pull a heavier rope over.

The Neo drone is better for this than my normal drone as the propellers have guards around them so the string doesn't get caught up when decending on the other side of the tree.

Installing FreeDV on Linux

In this video I walk through downloading, installing, running and doing the initial configuration of FreeDV on Linux. In this case I'm using Ubuntu 22.04 but it will be similar on derived distributions and I know it also works on Fedora based distributions.

FreeDV Sunday net - 19 stations

The biggest Sunday morning south east Australia FreeDV net so far this morning with 19 stations. Not everyone could transmit but I'm counting them anyway.

VK2DWG, VK2KNC, VK3AWA, VK3JF, VK3KR, VK3KEZ, VK3PCC, VK3SRC, VK3YV, VK1EJ, VK5LN, VK4BAP, VK5RM, ZL2TJM, VK2BLQ, VK3KVA, VK7DIK, VK3IK.

Great to talk with everyone and sorry I'm such a clutz at running the net. I need to figure out a better to run it than working through a changing list.

Installing FreeDV on macOS

To help newcomers I've made a video showing download, install and initial configuration of FreeDV on macOS.

My plan is to make a similar video for Linux but it would be wonderful if someone else could make the equivalent video for Windows users.

Tech Talk on ABC Radio

Atlassian is a hugely successful Australian software company that makes tools for software teams. Last week they surprised everyone by announcing the purchase of "The Browser Company" for almost one billion Australian dollars. 

Founders Mike Cannon-Brookes and Scott Farquhar financed the startup of Atlassian with $10,000 of credit card debt. Today, their market capitalisation is $45 billion US dollars. 

Peter Marks is a software developer and technology commentator from Access Informatics, joined Philip Clark on Nightlife to discuss the acquisition and other tech news. Listen here: https://www.abc.net.au/listen/programs/nightlife/tech-talk-with-peter-marks/105755424 

This morning, after the Apple announcements I had several requests for comment including ABC Radio Darwin. My bit starts at 1hour and 6 minutes here. Host Adam Steer is a bit of a skeptic and has nostalgia for his old Nokia tradie's phone.

FreeDV Sunday net - 14 stations

The weekly FreeDV net on 40m in South Eastern Australia was excellent this morning despite wet weather here. Mark, VK5QI had planned a balloon launch that had to be delayed for the same reason.

7177 was busy so we moved to 7197 which caused a bit of confusion for a few minutes.

Stations on the frequency included VK2ATW, VK2TTL, VK3AWA, VK3BRT, VK3KEZ, VK3SRC, VK3YV, VK5GY, VK3KVA, VK5LN, VK5QI, VK5RM and ZL2TJM just listening but said "hi".

Thanks everyone for participating.

Is high octane fuel worth it in a Toyota Corolla Hybrid?

I was wondering if high octane petrol was worth the extra price. I asked two car oriented friends recently and they both said “absolutely - wouldn’t not use it”. Another friend said it has no effect except on high compression engines which modern cars are not.

Anyhow, I’ve been doing an experiment. I let my Toyota hybrid run very low on fuel and filled it with 98.

Here's what I see after a tank of Unleaded 91 fuel:

Here's what I'm seeing after a fair amount of a Premium 98 tank:

Normally I get 4.3 l/100 km. On high octane I’m getting 4.1 l/100 km. So it seems to make a small difference but not enough to justify an extra 20c per litre.

Here is where I fill up locally:

As is normal for a headline that is a question, the answer is no.

FreeDV with VK3SRC and VK3CKY

Just a little off air recording of some local stations talking with FreeDV RADEV1.

Joe VK3SRC asked about those "wings" (as he called them) on either side of the main carriers. He hypothosised that they were extra error correction signals. In fact they are an unwanted side-effect of the current RADEV1 code that will be removed in a future version.

To test this he used filtering in his transmitter to nicely remove them. You can see a "normal" signal at the bottom and his frequency limited signal above:

The resulting signal was perfectly decoded and has less wasted transmitter power.