Getting electronic components

**irving2008** · 14-08-2009

Originally Posted by Ross77

They sure do. should have to enougth to build 10 boards. £15 of that was for a logic probe.

Do you not need one on the output chip as well? How are the PMINMO boards? I nearly bought a couple the other day, but I really wanted something with the dual output chips to get 4amps, dont like running things at max power.......

Yes I do, i have a piece of 20mm finned ali 150mm x 100mm that three will be bolted to.. But for testing with the current set for 0.5A the L298 needs no heatsink, but the total draw on the 5v rail by the L297/L298 combo is 100mA so at 36v supply (26v into the 317) the 317 gets too hot to touch.. it actually verges on the temp limiter after a while and the 5v drops out. So a small heatsink is needed.

The boards are really excellent quality, recommended.

Incidentally the thing that looks like a clothes peg on the top LH corner of my base board in the second pic above is in fact.... a clothes peg... screwed down, with a length of 16awg wire (otherwise known as a cut down coat hanger) taped to the top and bent over at the end with a filed and flattened point. Its used for holding SMD devices against the board while they are soldered (Phil likes using SMD decoupling capacitors for on his boards)...

**Ross77** · 15-08-2009

Incidentally the thing that looks like a clothes peg on the top LH corner of my base board in the second pic above is in fact.... a clothes peg... screwed down, with a length of 16awg wire (otherwise known as a cut down coat hanger) taped to the top and bent over at the end with a filed and flattened point. Its used for holding SMD devices against the board while they are soldered (Phil likes using SMD decoupling capacitors for on his boards)...

What a good idea. I was going to ask how you got on with the SMD bit. I'd heard that you had to glue them on first, which could be a problem if u accidently fry it whilst soldering.

**irving2008** · 15-08-2009

Originally Posted by Ross77

What a good idea. I was going to ask how you got on with the SMD bit. I'd heard that you had to glue them on first, which could be a problem if u accidently fry it whilst soldering.

So had I, but I was also concerned about getting a thin enough area of glue so that the chip sat down on the pad and not gettng glue where it shouldnt be. Glue and I are not compatible!

The idea above is not mine, Phil outlines it in the assembly guidance for his boards, but I adapted it to what I had - the coat hanger wire is a tad too thick but its all I had to hand. here are some more pics, showing one of the 1206-style chip capacitors in its protective strip and the chip held to the board by the wire device (but not finally positioned yet)