Monthly Archives: November 2017

Poor Man’s Signal Generator

AD9833I can’t remember how, but when messing around with scopes and awaiting my new signal generator (more of that in the coming weeks), the AD9833 Programmable Waveform Generator came to my attention.  Take a look at this Ebay link. This would you believe is a signal generator. Without those connectors you can purchase the board even more cheaply. So I paid £5, you can get  boards at half of that.

How would you like a dirt cheap signal generator with:

  • 1hz-12Mhz range
  • 4-button operation (6 buttons with 2 memories)
  • Sine, Square or Triangle Outputs
  • Non-volatile settings
  • Audio button feedback

And there’s more. Read on…

Continue reading Poor Man’s Signal Generator


Korad KA3005D Bench Supply

Just a quick one here as it’s all in the video below. This is about the  Korad KA3005D Bench Power Supply – a nice solid unit able to provide up to 30v at up to 5a.   I had visions of some lightweight switched job – but no – a honking great transformer inside.

4 memories, voltage and current limiting AND optional cut-out, fine and course controls for voltage and current and – not expensive.

All in all very nice – but for two things – no English manual (but that IS available online) and it came with two power cables neither of which were British – but apart from that – spot on – see what you think. Anyone got one? If so how is it working for you? I wrote to teh manufacturer about M5, not only did they send me an up to date manual but immediately cleared up the question about the M5 indicator (as did readers of the blog and video).  Select memory M4, turn the dial to the right and you're talking to memory M5.

Yes I’ve had the scope out – 5v 4 amps – the output hardly budged (a few mV) and no appreciable noise output.

Using a meter I trust (for now, until my precision voltage reference turns up),  the output from the power supply off-load was in all cases within 0.22% of my meter reading!!   On the 5v out setting, I applied 2.33 amps load and the output voltage dropped 0.41%

Again at 5v, with a 4.66 amp load, the 5v output dropped 2.01%

Other power supply stuff from Banggood here.


INA219/ESP8266 and Node Red

tmpB2D1In a previous blog entry we were playing with the INA219 voltage and current monitor. Here I team the little board up with the ESP8266 and Node-Red.

In this entry, I have teamed up the INA219 with my ESP8266 code which already has a driver in for this chip and also has support for the SSD1306 – hence, thanks to MQTT, this little combined chip can easily show the current status on the on-board display and also show it on a Node-Red dashboard in gauges and also a combined graph.

Please note that I have updated the ESP8266 code (v2.3.15) and changed how this works as I ended up writing way too fast to the device… this code works.

Power MonitorOf course that’s how I’ve done it – armed with info you can do any variation you like. I’ve set the graph limits here to 6 volts, I guess it would make sense to set it to 30v.

I’m also using a 1 second inject node, perhaps something more flexible and externally programmable would be better – in which case you could have different graphing speeds. Nice for checking battery charging?

As my ESP8266 code (documented on the blog – see right menu, ROMS available, recently updated) already does all the display and INA219 handling, everything was done in Node-Red.


Power Monitor

Here is the code for “Process Chart”

var ina=JSON.parse(msg.payload);
var msg1={};
var msg2={};
var v=Math.round((ina.voltage/1000.0)*100)/100;
var a=Math.round((ina.current/1000.0)*100)/100;
var w=Math.round((v*a)*100)/100;

msg.payload=v; msg.topic="voltage";
msg1.payload=a; msg1.topic="current";
msg2.payload=w; msg2.topic="watts";

The injector node has a topic of ina219/toesp (assuming you set the ID of the board to “ina219” of course) and a payload (string) of:


The 1 on the end implies a 64 pixel high ssd1306 display attached, a 0 would imply a 32 pixel high display and no parameter would assume no display and simply send the information out. Initialisation of the INA219 and optionally the display happens at first use – no need for separate init.

I’ve now added range adjustment – you MUST have the latest node-red-dashboard for this…

return msg;

In the case of setting the maximum range to 6 – the payload for that button (drop down and select JSON) is {"ymax":6} – have as many as you want!!

And that’s it  - simples…

I’ve not shown current here as I need to lower that LOAD resistor on the INA219 but you will normally see voltage, current and power in that graph! Once I figure out how to correctly reprogram the chip I’ll add that into the ESP8266 INA219 code.

I have some 0.025R resistors on the way but from China so it’ll be weeks. Meanwhile of course this is perfectly usable.

The first version of the software proved unreliable and so anyone who first looked at this may have noticed I've updated the ESP software. The current version I have sitting on a window on my PC.

It has now been running at 1 sample per second for the last 96 hours without a glitch. At some point I'll add disk (sqlite most likely) logging - though in Node-Red that is simple enough to do.


The BitScope Mini Oscilloscope

Let’s face it, if you want an oscilloscope and logic analyser that fits in your shirt pocket, your choices are a tad limited.

Regular readers may recall that way back in 2016, I did a short review of the BitScope Micro, a VERY portable circuit board which, coupled with suitable software for the Raspberry Pi or PC, acted as an oscilloscope or logic analyser. Well, this is it’s “big” brother.

Continue reading The BitScope Mini Oscilloscope


LiPro Balance Charger

LIPRO BALANCE CHARGEREvery time I see a video about charging or testing batteries, I tend to see one of these shiny blue units (or similar) – so I thought it was about time I got one! 

The LiPro Balance Charger (or rather, a clone as we will see later) is pocket sized and has an input socket on the left… it takes from 11v to 18v input… and trust me it objects loudly if you put in a higher voltage as I did – beeps like crazy – but then that’s better than blowing up, any day.

I have lots of Lithium and other types of batteries lying around and some of the claims for them are bordering on the ridiculous – and I’ve always thought, wouldn’t it be nice to actually be able to CHECK the claims – and of course another battery charger never goes to waste. Read on…

Continue reading LiPro Balance Charger


INA3221 v INA219

tmp19F7Voltage and current monitoring

The INA3221 or rather one of the boards based around it, allows for a single power input and up to 3 power outputs –each monitoring voltage and current and all done via I2c.

You can (almost) think of this as a triple INA219 – the bidirectional current power monitor. If you recall, a little while ago, I added the INA219 to my ESP8266 software. I thought the INA3221 board might be better than three of the INA219 boards – but read on…

Continue reading INA3221 v INA219


A busy Week

It has been a busy week this week – with lots of new things happening.

Firstly, there is a brand new update to the RFLINK software, IMHO the best software around for decoding and transmitting signals for a wide range of RF devices – such as weather stations and remote controls – in my case using 433Mhz.  See the short video update I did on this one.

Here’s a link to a blog entry I wrote months ago on the same subject. tmpC114Then I’ve been working on the DPS5020 and DPS3003 power supply boards which have provided HOURS of entertainment.  I’ve spoken with the designer and I think this stuff has a good future because of the kind of direct support they are keen to give – and because the stuff just works. In a couple of weeks there’s a new board from the same source and when my new scope arrives I’ll be using that and the load tester to give it a hammering.

I’ve had a play with my little EM125 pocket (well, large pocket) oscilloscope and in the process of playing with these two, discovered the need for a decent signal generator and dummy load – both of these are on the way and will be covered in the coming weeks – along with some other exciting incoming stuff like a new 3D printer and a “proper” desktop scope.


MEANWHILE I’ve not gone off the boil with the uninterruptible supply, FAR from it but Aidan and I have been waiting for a PCB to turn up. It came earlier this week and we’ve been getting that working – of course, as you might expect, in the process of doing that we’ve thought of better ways of doing things, so the present PCB is going in the bin and a newer, smaller, better design will be forthcoming, most likely before Christmas.

Oh and not to  forget the new Alexa feature – using it as an Intercom – that is MARVELLOUS.

Lots happing in the next few weeks….so make a note to look in – or better, if you’ve not yet subscribed to the newsletter on the right panel of the blog) – please do!

A quick thanks to all of you who feed back constantly on the blog and on my videos and for all those who provide new ideas and new links – what a great time to be interested in technology.


DPS5020 and DPS3003 PSUs

DPS5020 Power supplyFirstly, the DPS5020 power supply comes in 2 parts, the main controller and a front panel. You get the pleasure of fitting it in a box – and supplying power. So it is “kind of” DIY.

In this case you get a programmable power supply able to give you up to 50v at up to 20 amps output.

But doesn’t that seem a bit daft, needing a power supply to feed a DIY power supply? Nowhere near as daft as it seems – read on – it gets a lot better…

Continue reading DPS5020 and DPS3003 PSUs


EM125 Handheld Scope

tmp696AIt was just like Christmas this morning. After a few days of no posty, a couple of packages turned up for me. Inside one of them, the EM125 Handheld Digital Oscilloscope. This large-pocket-size scope runs for up to 10 hours on an internal rechargeable batteries, has 25Mhz bandwidth and also acts as a voltmeter, diode and capacitor tester and resistance checker.

Continue reading EM125 Handheld Scope



For some reason this morning when I got up – there were more emails than usual – and amongst them – sales – so here’s just a quick set of links – in case you’re after some Christmas presents for yourself Smile  = I’m not saying they are good or bad, just pointing you in their direction just in case. Last week I got a hell of a good new phone cheap in the Banggood sale (and I’ll be on edge until it turns up in a couple of weeks) so sometimes there are bargains to be had.

Anyway, here they are – if you’re aware of more so called “Black Friday Sales” of note, do let us know (no, they didn’t ask me to do this)

eGlobal Central Pre Black Friday SaleGeek Buying Black Friday Sale, Banggood Black Friday Sale.


Node-Red and Alexa with Big Timer

tmp96D4I’ve recently updated my setup at home, finally doing away with HA-Bridge and I thought you might like to see this simple setup.

So for beginners, HA-Bridge is a piece of software (a very nice piece of software) that runs on for example a Raspberry Pi, who’s job (in my case) is to talk to Amazon’s Alexa and send off MQTT commands to control things.  In reality I’ve always had it return commands to Node-Red – because many of my controlled items are on timers and I need the two put together.

Continue reading Node-Red and Alexa with Big Timer