Search This Blog

Thursday, 22 June 2017

Another Whistle

I've just made a second whistle, this one is longer - in the key of G and, this time, using the black PVC pipe. I made the fipple block a bit longer and cut it at a sharper angle. This makes it a bit easier to play in my opinion.

If you didn't read my last blog, these are "penny whistles" made to the design of Guido Gonzato.

The black pipe makes a perfectly serviceable instrument, but it is much harder to see the pencil marks, and, conversely it shows the scuff-marks from sandpaper much more clearly! A strip of masking tape along the tube was useful to mark out the positions for the holes.
Here's a picture of the two whistles together.
73 Hugh M0WYE

Saturday, 17 June 2017

Low-Tech Whistle

I've got one of those cheap "Generation" tin whistles in the key of "D". It's quite fun to play, but it is quite high and squeaky and when I try to play with other instruments, it is horribly sharp. I like the sound of the lower pitch whistles, such as you hear played on tracks by Capercailie and on the Transatlantic Sessions television programs, but, although not very expensive, still looking at upwards of £50.

But I found an interesting website by Guido Gonzato here: Guide to making low-tech whistles

Now I have found designs for whistles before, but I have had difficulty getting the same materials as were used in the original. If you substitute a different type of tubing it has an affect on the length and hole position. But I found 2 meter lengths of this 20mm diameter PVC pipe in B&Q and Wickes for 99p and 18mm diameter hardwood dowel which can be made to be a snug fit inside by sanding off about half a mm.

So today I made one, and I am very pleased with the result (photo left). I won't go into detail about how I made it because Guido's instructions (in the above link) are very detailed and I followed them very closely.

I made the Alto B-flat instrument, and I found that I needed to leave the tube about 1mm longer than was specified in the diagram.

In fact, because my tube started out quite long, I checked his overall lengths at F#, G, G#, and A and found they all needed to be 1mm longer than specified - that probably comes down to the type of tube, he says "not all PVC pipe is created equal".

So I wanted to upload a sound-sample for you, but I don't see a way of doing that on Blogger, so it will have to be in the form of a video ...
Sorry I'm playing it a bit like a recorder, it's just to give an idea of what it sounds like! Guido has some much better sound samples on his website.

I'm intending to make some more of these, in different keys, and perhaps even longer and more mellow :-)

Anyway, if you like making simple musical instruments, I encourage you to have a go at making one of Guido's low-tech whistles.
Hugh M0WYE

Saturday, 10 June 2017

Lidl's Vice

I've got a variety of bull-dog clips, clothes pegs and "extra hands" to hold small items when soldering. I did have a small table-top vice, but my son "borrowed it" and it has obviously proved very useful to him ... haven't seen it since :-)

When I saw that Lidl's were offering a table-top vice for eight quid, I thought I would give it a try.
Lidl's Table Top Vice Offer.

Some of their tools are very good value for money, occasionally I have wished that they were better quality!
This product seems ok ... but there are some important things to be aware of. One is quite obvious when you pick up the box in store - it isn't very heavy! It is not made of steel, it is made of an aluminium alloy (clearly stated in the instructions) and this means the casting is not going to be very strong. Don't expect to use it like an expensive Record vice for hammering and bending thick metal, it will break.

The aluminium will likely not be as hard-wearing as steel would be.

The main tommy-bar, used for tightening the jaws of the vice is quite nice, with a detent at each end, so that the bar clicks into place at each end of its travel. However I found that all the screw threads felt rough and "graunchy" - not smooth at all. Although the instructions make no mention of lubrication, the first thing I did was to apply grease to all the threads and the grooves where the moving jaw of the vice slides. I also greased the ball and socket and now it feels much nicer to use.
hopefully that will extent the life of the threads a bit too. Time will tell.

The vice is supplied with soft, plastic covers for the jaws, which could be useful for holding some items, but will obviously be useless for soldering, because they will melt! Underneath the plastic covers are smooth metal jaws, one of which has two grooves at right-angles. The grooves are for holding round objects.

Supplied with the vice is a clamp for holding tubes of between 38 and 43mm diameter. This seems rather a limited range to me, and it is complicated to fit the tube attachment. To do this you have to remove a the jaws, which requires the use of the supplied hexagon wrench. However, the fact that the jaws can be removed does allow for the user to create their own attachments.

I'm thinking that this will be very useful for holding plugs, sockets and circuit broards instead of chasing them round the bench with the soldering iron.

Hugh M0WYE

Sunday, 4 June 2017

Oh bother ...

Wondered why I had no audio this morning. Went to unscrew the cover on the mic jack and it fell apart in my hands. Yuk! cheap plug. Now replaced by a gold plated on - hopefully last a bit longer!

Wednesday, 31 May 2017

TYT MD380 Hands Free Kit - in use

Thanks to Colin G0PHO and Bradley M0XBW for the on-air test today - and enjoyable mobile QSOs! I can confirm that the hands-free kit is working well.
I thought I would add this photo of the radio in the car, although it is a little confused because I still have the wiring for the FT60 handheld here too. There are two toggle switches taped to the cigarette lighter plug, bottom right. the left hand one is for the DMR radio.
The "well" in which the radio sits is in the centre console and the TX/RX switch is just in-front of the gear lever, so it is easy to find without looking.
I use the internal battery of the radio. In the old days you could get more RF power out by running your handheld on 10 or 12V derived from the vehicle supply, but the modern radios produce just as much output when running from internal batteries. Also, this approach prevents alternator whine and ignition noise from the car electrical system appearing on the transmitted or received audio.

The cigarette lighter plug here is a mobile phone charger and nothing to do with the radio set-up.

There are a couple of general comments I would like to make about the TYT MD380, in case you are thinking of getting one. I find the display quite difficult to see out doors in daylight - quite impossible if the sun is shining on it. The colour display is very pretty indoors, when the backlight is on, but goes completely blank when the back-light switches off. I find I am constantly twiddling the volume, or pushing the power up-down button just so the light will come on and I can read the screen.

Also the radio is supplied with a charging stand - with a nice LED that is red when charging and goes green when it is cooked. I like that, but it is powered by one of those horrid little plug-top power supplies and it generates S9 noise right across the 50MHz band - ughh! I don't think it has any filtering in it at all, such a shame for an amateur radio product, and makes you wonder about the safety of the device if they can't be bothered to meet EMC requirements. So no chance of using six meters when the radio is charging.


Sunday, 28 May 2017

Hands-free kit for TYT MD380

I have finally got round to it!
To my shame I see it was nearly a year ago that I worked out the microphone and speaker connections on my TYT MD380 handheld - see the blog here:
Mic and speaker connections for TYT MD380

I have a home-made hands-free set up for operating mobile with my analogue handheld (an FT60E) and I would like to use something similar for the digital radio.

The microphone is a small electret condenser capsule, mounted on a microphone boom of galvanised iron wire (coat-hanger wire!) which is attached to a baseball hat. The microphone is quite close to the mouth, but not directly in front to avoid breath-blast. When I made my first version, I stitched the wire to the front of the cap, which was quite time consuming. The current one is glued to the back of the brim with hot-melt glue. Not very pretty, but quite quick to do.

The transmit switch is a toggle switch that is taped to the side of a cigarette-lighter plug that is located very conveniently beside the gear-change stick. This makes it very easy to flip between TX and RX without taking my eyes off the road. And also doesn't involve drilling any holes in car.

I use a Diamond dual-band mobile antenna on the motor car, mounted on the tailgate and connected to the radio via RG58, a BNC and one of those BNC - SMA adaptors.

On the radio, under a plastic cover on the right-hand-side are two sockets, a 2.5mm diameter jack and a 3.5mm diameter jack. These are dual purpose, the 2.5mm one is used for the speaker connection, the 3.5mm is used for the microphone, and the radio is put into transmit by connecting the ground connection of the microphone to the ground connection of the speaker. The two sockets are also used for a USB type serial link for programming the radio - so don't connect to the unused terminals on the connector they are for data transfer. I used a cut-down, ready-made,  2.5mm audio cable, to avoid soldering to a rather fiddly plug.

So here is a diagram showing the connections to the radio. Note how the microphone positive is connected to the ring of the 3.5mm jack, not the tip. Leave the tip unconnected. Also leave the ring on the 2.5mm jack unconnected, these are the data connections. See how the transmit/receive (PTT) switch is wired between the speaker and microphone grounds. It is important for the microphone to be wired the correct way round, because the radio provides power for the FET amplifier in the capsule.
Here is a picture of the wiring before I covered it all with electrical tape. We don't want any short circuits. But it is always best to test it all before covering it with heatshrink or insulting tape.

Here is the complete set-up. A more glamorous baseball cap would do wonders for the appearance of the equipment ... so would a more glamorous radio ham.

A note about the loudspeaker: I use a cheap car radio speaker because it is in a nice plastic pod, which I can put on the centre console of the car. The radio specification calls for a 16 ohm impedance loudspeaker. The car radio speaker is clearly a 4 ohm part. The radio does seem to work ok with an 8 ohm speaker, but I thought 4 ohms was pushing it a bit. I used a transformer to convert the impedance. I am using just the secondary of an audio output transformer. The winding has a centre-tap and I am using it as an autotransformer. The radio is connected across the whole winding, the speaker is connected between one end and the centre-tap. This gives a 4:1 impedance conversion. The primary of the transformer is left unconnected. Hopefully you will be able to find a more suitable speaker and not have to bother with this!

Testing: I first checked the speaker connections, plugging the 2.5mm plug in and listening to the World-wide talk-group on the local repeater. When all was working on the receive side, I made sure the TX/RX switch was "off" and plugged in the 3.5mm jack. Now, on our local repeater GB7AS, we have a special Talk-group on Slot 2 which echos back the transmit audio after a short delay, for people to test their radios. This is called TG9990 Echo Test. If you don't have this, then you will have to get a friend to listen to your audio and check it is working well. you can see if the TX/RX switch is working because the LED on the top of the radio goes red in transmit.  Have fun!
Hugh M0WYE

Friday, 26 May 2017

Ermine Moth

I notice that there are a few places along my route to work where the hedge is festooned with what looks like spiders web.
A closer look reveals that the culprit is not a spider, but lots of caterpillars.
This last happened in May 2011 (I still have the photos I took then!), and a bit of research then revealed that these are ermine moth caterpillars, and their host plant, is the spindle tree.
On the Wikipedia page there is a picture of the moth, but I have never knowingly seen one of the adults.

The plant has been completely stripped of leaves, but in 2011 the bare twigs sprouted new leaves after the caterpillars had gone. It can't do the spindle tree much good, but it does seem to recover. So I hope it will do so again this year. I notice that the parts of the hedge which are affected are all close to telegraph poles - not sure if that is coincidence.

Since I travel this route almost every day, I think I would have noticed if there had been similar tents in the hedge between 2011 and 2017, but I don't recall seeing any. So that raises the question is this a regular event occurring every six years? or is it just the climatic conditions have been ideal for the caterpillars? At the moment ... we just don't know ...
Hugh M0WYE