View Single Post
Old 28th Dec 2018, 8:10 pm   #96
David G4EBT
Dekatron
 
David G4EBT's Avatar
 
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,737
Default Re: Building the 'Minimod' AM modulator-questions!

Quote:
Originally Posted by Ian - G4JQT View Post
Quote:
Originally Posted by David G4EBT View Post

Having drilled more than 1,400 holes on sixteen Mini-Mod PCBs in recent weeks [...]
Just curious David, but how many boards have you made all together? I must have built and dispatched about 30 MiniMods in total over the past few years. There must be getting on for a dozen built by forum members, so wonder how many there are out there, and how often do they really get used I wonder?

Ian
"How many have been built and are used" is a good question, the answer to which is anyone's guess!

Back in 2015, I made 3 mini mods - one for myself, one for my son and one for a friend.

I'd used your original PCB layout as a guide to design my own PCB and posted that on the forum at post #85 in this (now closed) thread:

https://www.vintage-radio.net/forum/...t=98221&page=5

I posted the layout for anyone to use if they wished, not intending to make boards for other forum members due to time constraints. I'd suggested that anyone wishing to make a PCB who didn't have UV facilities might wish to try the 'toner transfer' method, which only calls for a normal laser printer. Having transferred the toner to the PCB laminate, the board can be etched and drilled.

I did however end up making ten boards for forum members back in 2015 in addition to the three Mini-Mods I'd made myself.

That thread went to sleep in August 2015, then on 8 Sept 2018, this thread brought the Mini-Mod back into the limelight. I updated the earlier PCB design, still using your original component placement Ian, but leaving more copper on the board to reduce etching time, and to give the best chance for anyone who doesn't have a decent mini-drill and stand, to allow a bit of leeway for misaligned holes.

I built another Mini-Mod using that updated PCB layout to make sure it worked and was stable, which proved successful. Since 2015, the UV ‘dry film’ technique has come to prominence which requires negative artwork. For anyone who still uses positive resist boards or wanted to try the toner transfer method, I posted the positive mask as well as the negative one, in post #65 in this thread.

Relatively few people had contributed to this thread at the time, and I was asked if I'd consider making a few PCBs. I said I could cope with half a dozen, which would have more than covered the interest shown in forum posts in this thread, so I made six and said that would be it. However, as with any thread, there is an unknown number of 'lurkers' who read threads but don't post. I don't use the term 'lurker' disrespectfully - that's the way it is with any forum. As a result, I received many requests by PM and just had to draw the line.

All told, with those I made back in 2015, I've made four Mini Mods and 33 PCBs.

This makes no sense for me as DIY PCB production is labour intensive, can't possibly be put on as commercial footing, and that's not what I'm about - I'm a hobbyist, pure and simple, enjoying my 25th year of retirement in my twin hobbies of vintage radio and woodturning/woodworking. I like to gain inspiration ideas and advice from others, and to share my own ideas for others to maybe replicate or improve upon.

Ordinarily, I have little 'hobby time' but at end of May I had a knee replacement operation, so I was 'grounded' for several weeks. As I'm a fidget, to keep me occupied, I etched a quantity of PCBs for the FM/AM converter and built and tested some boxed-up converters as well as Mini-Mod PCBs. I'd like to think that the PCBs have all been built and put into use rather than requested and put in a drawer to be built sometime/never. I know that some have been successfully built as I've had follow-up responses.

I believe that there are firms who will produce PCBs at very low cost to a very high standard, but to do so, they require ‘Gerber Files’ which are a complete mystery to me and will remain so. At post #74 in this thread, Terry, VK5TM very kindly converted my PCB layout to a Gerber File and attached a jpeg of the component layout. Anyone wishing to get a PCB (or a batch of PCBs) made professionally to that design is welcome to do so. As far as I’m concerned, it’s in the public domain. Ian conceived and designed the Mini-Mod and the original PCB layout – I just copied his component layout down to the last hole, and re-jigged the artwork for my own needs.

The Mini-Mod is certainly a great little performer and an enjoyable project to build and use.

I’d like to reiterate that while I've been very pleased to have helped several forum members with PCBs, I can’t cope with making any more for this or any other project due to time constraints.
I'm almost fully recovered from my knee replacement op, so I'm up and about, gadding about all over the place - Liverpool, London, Essex, Nottingham, York, fully engaged in family life as a husband, father and grandfather, and that's as it should be!

Waffled David, duty windbag.
__________________
David.
BVWS Member.
G-QRP Club member 1339.
David G4EBT is offline