Narrow-Bandwidth Television Association

gary wrote:It would be nice if a batch of very thin stainless steel disks of the right size for the MUTR could be ordered by the association and offered for sale.

I made this suggestion a couple of years ago, but it hasn't been taken up for some reason, when I come to the point of needing a disc this is how I intend to do it...

Using a single-sided fibreglass PCB cut to a circle and the holes drilled. Fibreglass shouldn't warp or bend and it's very flat and strong. It's available in thicknesses under the usual 1.6mm, less than 1mm I believe.

A PCB company can easily make this, no etching is required and it's all done on accurate CNC machines. To stop tarnishing of the copper a solder resist can be applied but the holes would need to be drilled after application or masked around the holes a small distance.

Alternatively no copper at all and spray it black.

I'm not sure about the costs which might put some off, but a batch of 10 or more hopefully shouldn't be that bad.

Just a suggestion...

Steve A.

Added later...It appears that 0.8mm is a standard thickness for PCSs.

Well the printed circuit boards for the "universal" televisor, derived from the MUTR circuit, arrived today from PCB Express and they look very nice. All the components are in hand so it looks like I will start wiring things up this weekend. It will take a bit longer to get everything packaged and connected to the DE Televisor mechanics, but I will keep everyone posted.

Ralph

Dear All

I've just joined NBTA having had an interest in television engineering for many years! I received my MUTR Televisor last week and got it up and spinning this weekend. I echo everyone's comments about it being excellent value and it works brilliantly. I must also thank Gary Millard for his 2 splendid programs that make scan-converting a doddle! Not to mention - streaming live webcam to the televisor - superb!

Thanks everyone for all their improvements - I've already changed the LED and diffuser and fitted the battery box with screws! Anyway - I thought it would be a good idea to fit a small audio amp to the unit and there is a great little Velleman "K8066 Super Mini Mono 3Wrms Audio Amplifier" available from Maplins in the UK for only £6 and I fitted that to the rear of the televisor, together with a small speaker (see attached photos). I obviously had to drill some extra holes and also fit a 47K pot on the input of the amp to set the volume and plug it into the audio out of the televisor board. The nice thing about this module is that it runs off 6V so I just hooked it into the existing battery box! Works great!

The other thing I found was the the line out from my PC (which I use as my audio/video source) is inverting. I noticed several posts here about building simple hardware polarity inverters, but I found a great little freeware plug-in called Flipper. This is a VST plug-in and will work with, for example, Roxio Sound Editor. It is a small DLL that you can load in Sound Editor and it allows you to polarity invert one or both of the audio channels. For example, I couldn't display the test files that came on the MUTR CD, so I ripped them to WAV files using Windows Media Player, loaded them into Sound Editor, inverted the video channel and saved it to another WAV file - worked a treat! You can download it at http://www.hitsquad.com/smm/programs/Flipper/

Anyway, I hope this is of use.

All the very best,

Neville

Nice work Neville, and thanks for the compliment, very much appreciated.

Thanks for the link to the 'flipper' too, I have added it to my collection.

I should point out though, that if you use TBP to output NBTV through the sound card (i.e. "Video Mute" option off) that it already has an "invert" option, so you don't have to modify the actual file. Also note that it can play directly from CD (digitally) so you can, if you wish, avoid needing to 'rip' the files off at all.

It dawns on me from reading your post that TBP should also support a webcam source, shouldn't it?

Cheers,

Gary

Dear Gary

Many thanks for this - I hadn't realised TBP could output to a sound card as well and play CDs - it really is a superb program!

Yes, it would be great if it could support webcams as well, like your Video2NBTV program.

Many thanks again,

Nevillle

I've found that a thin piece of plastic foam works well.What I used for both my first monitor and the club based one, I'm just finishing off, was a slice of the core from foam filled card from my local art and craft shop. Not sure exactly what its made from but looks like fine white polyurethane. The problem is separating the paper from the foam, I used a long thin blade from a decorators window paint scraper (Wilkinson). With that I can get an even thickness of about 4 mm.

Neville,

Welcome to the club (if someone hasn't said it already).

re adding an audio amp/LS. I'm going down the same path myself.
One good thing about the MUTR design is that there's plenty of space to add extra circuitry. The more I play with the unit the more I appreciate it.

I've tried different diffusers but the there's a trade-off between resolution and brightness. The one provided seems a reasonable compromise.

Nice photos as well.


Regards,


Graham

For the sound: use a pair of active PC speakers. They plug directly into the second jack on the MUTR PCB and the built in amplifier gives more than enough power for the sound. And although the sound isn't stereo, both speakers are giving you the sound. Place them left and right of the MUTR televisor. Makes a nice set.

A very usefull extension is an AC-DC adapter of 6 volts. This makes the battery box and the batteries superfluous and has the advantage that the voltage is better constant. I observe that when the voltage goes down somewhat the setting for correct synchronisation changes. This is obvious as:
- the voltage over the motor will be constant for the same speed,
- so the voltage at the drain (top) of the FET will change too,
- the feed back of that voltage into the circuit will change,
- this must be compensated by a different setting of R21.

Good idea Klaas,

Regards,

Graham

Thanks for the 'welcome' Graham - much appreciated. I too have experimented with different diffusers and have reverted back to the supplied one. I replaced the supplied LED with a Superbright Orange from Maplin. I also made another LED PCB and fitted that with a Superbright white so I can easily swap between 'best picture quality' white and 'authentic neon' orange!

I may well fit a another small socket so I can take up Klaas' tip about an external PSU. What is nice 'though is the portability of the unit so I can bore friends with it easily We have some friends coming for dinner tonight - they don't know what they're in for!

All the very best,

Neville

An update on my MUTR.

I've added an aperture mask to hide the extra images above/below the main.

I've knocked up a small add on board with an audio amp, and inverting amp with gain/LF EQ for the video channel.

My el cheapo £10 Argos CD player showed LF roll off on track 20 of CD1 (the grey staircase) with quite severe LF tilt/curvature. and inverted video.

The LF Equalisation compensates for this with almost 100% perfect results, leaving a flat base line and improving synching.

(I've also included a non-inverting version. I've run this on Electronic Workbench, but not actually built that version, whereas the inverting version has been simulated and built.)

Regards,

Graham

I look forward to seeing this "Super-Muter" in action at the convention! Well done Graham.

Steve O

Thanks Steve,

Cheers,

Graham

Greetings all - my first post here. Thanks all round for the helpful suggestions re the televisor kit (I've always wanted something like it since acquiring 9 issues of the magazine "Television", dated 1928).

To stiffen the disc I've used an old CD, stuck on the front with double sided tape. It's exactly the same size as the strobe pattern, so no fowling of the holes. There's also the added bonus of mass, so the disc now acts more like a flywheel. The disc rim can now be got very close to the light sensor without touching anywhere. Those of you wanting to offset the strobe pattern slightly could actually copy the original and then print it out onto a white printable CD or DVD, and stick that on the rear of the disc, thereby killing two birds with one stone. (I suspect the original strobe is itself printed onto a self adhesive CD label.)



The motor definitely is more stable with a load across it, and a small 12v bulb serves well - 12v 3w seems OK (48ohm), and although this may be a lower load than others have suggested (I recall 12ohm suggested), I am using a stabilised power supply, set at 4.5 volts, and this works perfectly in this setup, at least for home produced CDs made up of old video clips from YouTube (BFI have lots of these). However, at this voltage the onboard testcard will not work. I just get good results from the CDs.

I apologise if someone else has already posted any/all of the above elsewhere and I am re-inventing the wheel!

That's all folks

Regards

Terry

Hi Terry (Judget)

Welcome to the forum.

Interesting hearing how others mod the MUTR kit.

Cheers,

Graham