Jol Wilkinson wrote:Dave,
as the owner of LRM is a close friend of mine, I"ll leave you to work out your own RSU spec. Maplin used to sell a suitable transformer kit on which you could wind your own secondary outputs, but these are no longer available. I wound my own when the LRM unit was being developed but later replaced it with a professionally manufactured LRM transformer which was better.
The carbon probe is the easy bit, making a good probe holder is more difficult, which is why the LRM version is sold as a spare part and has been bought by owners of other makes of RSU.
sometimes there isn't a good "connection" between the carbon probe tip and the workpiece. I keep a small piece of card near the return plate and rub the tip lightly on that. If I can write with it it is clean enough to work. The RSU voltage is low and won't always work on dirty or oily metal, so cleanliness is important.
Thanks re the probe
What I was looking for was the type of current needed to solder brass kits , I dont see the need for for low voltages as 1-2V , I suspect 4V is sufficient. I was have to custom wind the secondary , but that's not difficult
Edit , I'll use a triac based input control to reduce the output rather then custom wind the Traffo , it would seem that 4V may be on the upper end for brass kits , so I will have lower voltages via the electronic input control
Anyways , I have found considerable information on the " net " , I'm going to use a standard 0-6V toroidal Traffo, 50-100VA with electronic control on the input voltage , allowing me to control the output down to very low voltages . I can source carbon rods from welding supplies and modify an old soldering Iron body.
I am a professional EE , so in theory I should know what I'm doing