Broxie

Microphone for Laptop

The Covid 19 Pandemic has given me reason to use various video and audio type conference applications in order to access training and social gatherings.

Although my Laptop Computer has these built in, I don’y actually use my laptop as a laptop. It sits up on end with the lid closed. Connected to it is a monitor a USB keyboard, Cordless USB mouse, and an Ethernet cable. It is a close to being a Tower as a laptop gets.

Until the first online meeting I had not even given it a second thought. I joined the meeting relying on the built in microphone. This microphone I had to virtually shout at for the gathering to be able to here me.

The group wanted to see each other and so I figured I would hook up a new unopened albeit several years old Web Camera that has a built in Microphone. That solved the video issue, but being mounted atop a large monitor several feet away, I still found I have to raise my voice to be heard clearly.

If I moved the Webcam closer to me the mic was fine, but then the video was too close in for me and I did not really have anywhere to mount it.

I ordered a couple of cheap vintage style microphones from “AliExpress”.

So while waiting for them to arrive I raided my old salvaged parts bin and set about rigging up an Electret microphone to the Dell Inspirations Headset port.

I do not have one of the TRRS plugs to test the voltages on the Dells socket. I did have a TRS one though as found on standard old style earphones. The output is only about 2 volts using that plug.

Looking around the internet I noted that a Bias resistor and a coupling capacitor are recommended. The resistance apparently between 1K and 22K Ohms. The Capacitor between 1uF and 22uF.

I was getting better results directly attaching the Electret without either of these components.

I tried all sorts of combinations and even tried paralleling a couple of Electrets. Nothing was much better then the Webcams Microphone when more then a few inches away.

My attempts at amplifying them proved useless using the 2V bias voltage available. I might build a little battery powered microphone amplifier at some point.

It occurred to me that I had a Microphone on a little Arduino board delivered recently. I hooked that up and the signal was much improved. At first I thought the on-board microchip was giving amplification. I sourced the datasheet to see if I could employ the same technique.

looking at the circuit diagram the analogue signal simply went through a 150R resistor!

One of the cheap microphones arrived. The signal was again not a lot better then the Webcam Microphone. However, I could now move the Microphone around the desk.

Opening the Vintage Style microphone which has a little switch to enable or disable it. I noted it had an Electret that looked very much like the one from the Arduino. I tried paralleling them but the best output was still from the Arduino’s Microphone Module.

I took a look and they had different part numbers. The Arduino Microphone “CZN-15E” a search suggests these specifications “Microphone 2 feet 50~60DB The sensitivity of 54 “.

The Vintage Style Microphone is just marked SG. These seem to come in various sensitivities . The nearest I fond on a search of AliExpress was this “6050 Microphone capacitance electret SG electret microphone 6050p/9767p pin 9767 microphone pickup”.

For now the two microphones have swapped laces. The higher sensitivity is now installed in the Vintage Style Microphone where it seems to work well. I will test it next time I have to do the video conference thing.

I might order a selection of Electrets from AliExpress to compare at a later date.

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Air Pump Repair and Upgrade

My cheapo air pump failed. I had thought to replace it with something one that lets you set the desired pressure and auto stops when the desired pressure is met.

That automatic type also often have the benefit of a back lit display, which would be handy in the underground parking area, which is where I normally where I use the air pump.

The cheapo pump does not have any illumination and I normally have to use the touch output of my mobile phone to see the pressure gauge.

The pump also lacks a switch, so when the pressure is about right I have to lean in through the car to disconnect it from the power socket.

The UK remains in lock down so a trip to buy a pump when I could possibly repair the existing one seemed wrong.

The repair itself was simple. It turned out the ground wire had broken off inside the 12 volt connector. There was zero strain relief inside the connector, so I added a cable tie and a little superglue to make a strain relief.

If I was still going to use this pump then I wanted to fit some kind of light. I figured I would us a white led of some kind. I was looking around for the best place to mount it and noted what looked like a 5mm led mounting. I assume that the pump might have a lit and unlit option.

The other feature I wanted to add was a switch of some kind. I salvaged a rocker switch with 5 amp at 120 volt contacts on it from a dead piece of electronics. I had to cut out a suitable hole the press mounted switch. The current offload is around 4.5 amps, so I think it will be okay but it could fail.

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Insulation Tester

While purchasing some items from CPC Farnell, I took a peep into the sale area. That proved a little costly as I spotted a insulation tester. I would not normally buy such an item without doing a bit of research but I took a leap into the unknown and bought this insulation tester.

I have never owned a insulation tester before and figured the ability to test the insulation with something a bit better then the ohms range on my cheapo old multi-meter might be useful from time to time.

The instruction book is written in broken English. Fortunately the functions of the unit are reasonably simple to work out with a little trial and error!

II think maybe I will eventually get something that can test up-to 4kV as the 1kV range seems a little feeble. However for the price the unit seems quite okay and is better then no tester at all.

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FE9600 Earth Bodge

In between ordering this Function Generator and it arriving from China, I happened across a Youtube (https://www.youtube.com/watch?v=FaNvHQW_CsQ), in which Steve pointed out a couple of issues with the unit.

The Earth to ground lead needs better isolation and the glass fuse should be ceramic.

Also mention was that the unit can run hot. I spotted the main board has a underpopulated fan connection and the back panel has a mounting port for a 40mm fan.

I measured the fan output at 5V DC, so I will order a fan.

I stripped out some earth wire from a 2.5mm cable but the inner diameter was too tight to slip over the existing wire. I have no sleeving or heat shrink, so maybe I should get some.

Giving up on this a recalled a I some connector kits so I decided to replace the wire. My kits have some male and female crimp connectors. I discovered that the female connectors supplied do not even fit in the header that is supplied in the box. They are all designed to be used with smaller cables then the 0.75mm I had stripped from some mains flex too.

Until I can get a suitable crimp for the connector and hopefully one that will take the cable. I have paired down half of the wire strands and crimped the remaining strands into a connector. I have used the strain relief section as an extra crimp onto the copper wires as the mains insulation is way too big for the connectors strain relief to cope with.

The Original connector

As I had desoldered the ground wire from the IEC socket I installed the new Earth wire with a spade connector. It is likely I will be inside the unit again so the ability to unplug the back plate seemed logical. I spent ages looking for a back full of the spade connectors, but they seem to have vanished. I must get more ordered.

I could not read the value of the glass fuse so I desoldered it. It is marked 2AL 250V. Ceramic 10mm fuses with wires are available in Fast and Slow Blow versions. Before I order them I must decide if I am going to replace the existing supply or not.

Steve designed a complete power supply but this came in a a hefty price and was largely surface mount. I am not really equipped for or experience in working with SMD.

The other suggested cheaper option was to use a couple of modules available form china. The issue here is that apparently I would need to design some filter to remove the noise. It would be worth pursuing if there is a compelling reason to remove the existing supply, but if all that’s wrong with PSU board is the glass fuse then it would be a lot simpler to just order a ceramic fuse for it.

I will have to watch the video a bit more to try and work out why Steve went to such trouble and expense upgrading this otherwise bargain basement function generator.

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Power Tower Repair

I purchased 5 tower type mains extensions for use around the home. I got them from Farnell CPC so I was quite surprised to find 2 of them were faulty. There was power to the sockets and the “Surge Protection” neon indicator glowed, but the “Mains On” neon indicator was extinguished.

Surge Protection Circuit

I contacted CPC to negotiate either the replacement of the faulty items or a partial refund. I had suggested that they gave me the price of one unit off the value of my invoice. Rather annoyingly they would only give me £4 off which was little more then half the cost of a single unit. I was tempted to sent them back for a full refund at this point, but that would mean packaging them and posting them back, which was more hassle then living with the fault.

It is a shame rally I have only recently started buying items from CPC rather then “Aliexpress”. I would have thought the customer service would have been a little bit better then it was.

Anyhow having decided to keep them and being informed that if I did my warranty would be void! How they would distinguish between the 3 items that did come to me working and the 2 that were supplied faulty is not clear to me.

I cracked them open and found both had the same leg of the neon broken. I simply soldered them in place and all works fine.



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Flux Inductor

If Doc went back to the Future with his Flux Capacitor then maybe Broxie can go Forward to the Past with some Flux and Inductors.

Having cleared out virtually all of my junk bin, namely several large plastic creates full of old electronics and cables of all sorts to stave off yet more visits from the “Hoarder Police”. I found that even building something as simple as the “Joule Thief” was quite a challenge to lay my hands on even simple things like some enamelled copper wire or even some ferrite cores.

So while ordering some other items these nice rolls of enamelled copper wire accidentally ended up in my shopping cart!

My only issue now is keeping them on my workbench as my wife loves anything copper or bronze like. It appeals to her inner Steam Punk!



I have found a ever growing need to use flux to re flow solder when trying to work on PCB’s. In the past I would tend to apply more solder, suck up the solder with a desolder pump and then add fresh solder. However with components getting ever smaller and my eyesight getting poorer, I am finding the need to apply flux to help re-flow solder and solder wick to mop up excess a better route. Talking of solder wick I ordered some in various widths. They have mysteriously vanished.

I ordered the switch cleaner after I discovered all of the switches and potentiometers on my Hameg oscilloscopes were giving poor contact. I was going to order some “Isopropyl Alcohol, but the price has gone through the roof. The demand for it rose sharply as the world is currently under attack from Covid 19 and hand sanitizer made from Isopropyl is now like gold dust.


I do not have an immediate use for Freezer Spray, but it could be handy to have here if I ever get to trying to fix things at are getting too hot.

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One PCB to Ruler them all

When I started out in Electronics and was building things there really were not any Surface Mount Devices. I had a basic understanding of the basic packages for most of the common components.

I used to make PCB’s with rub down transfers or by drawing with etch resistant pen. Most boards were either single or double sided.

I have not even attempted to make a progect using SMD components. Simply sourcing and attempting to replace SMD seems way more complicated then way back when.

I spotted this little ruler while shopping for parts and figured it would at least help me to identify package types a bit easier.

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Bread Board

I spotted this handy looking breadboard while ordering some other items and popped it into my basket.

Hopefully it will have enough room for when I am tinkering. Up till now I have ended up expanding onto several smaller boards, non of them are the same shape or size so I don’t join them together psychically.

I rather like the Terminal posts and the fact that this set of boards are mounted on a sturdy metal plate which has feet to lift it clear of the work bench.

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Brother Label Printer

A few days after seeing “Big Clive” review of a Brother E300 Label Printer, my wife and I went shopping for our first time in Cost Co. It turned into an expensive trip as I came out clutching a padded office style chair, a “Brother Label Printer” and a 4 pack of TZe cassettes for the printer.

The printer is model H101C. It uses TZe cassettes like the ones in the review, but has a few less features. Most notably it does not do the cable marking around the cable, however it can still do the cable flag type labels.



It has come in rather handy doing jobs like labelling my component draws and labelling mains plugs. I have had to purchase another pack of 4 tapes already.

Nods to “Big Clive”.

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