Looks good ,I may need to get the gerbers as well, but Is there any way to have headers line up right over the existing load sockets? Single pin headers would be fine.
Athanasios
Rotary SUT Load Switch
- Thread starter AvFan
- Start date
Looks good ,I may need to get the gerbers as well, but Is there any way to have headers line up right over the existing load sockets? Single pin headers would be fine.
Athanasios
HalfApt
Well-Known Member
Greyhill makes all their switches in adjustable-stop versions, it's a matter of finding them in-stock. Mouser doesn't have the 71 series in-stock. Someone else may.
1/4w, same as used on main board.
Footprint for 5mm pitch pins. Max size 7.5mm long x 2.5mm wide, PP film or MLCC ceramic. Caps larger than that would require a proportional increase in board size.
Yes. Pin-for-pin correspondence to switch pins.
On further pondering, there may be a bit of concern. With mounting holes at rear corners, this board will be fully cantilevered out. I have no idea how heavy the board will be with both switches & all the parts, so it may need some kind of vertical support at the front corners. Rigid drive shafts to front panel may or may not suffice. Keep that in mind for the rest of this post.
Q: do you want the interconnect wires on a socket/header as depicted it the previous example? or directly aligned with the main board load resistor pads as shown in this example?
There are other ways to do the layout as well.
This one moves the mounting holes forward, alleviating cantilever concerns, but the board is no longer flush to the end of the main board, extends backwards a bit, and it's not possible to align the wire pads with the main board.
And this one reduces board size as much as possible. Cantilever not AS much, but still more than the above. The circles on either side of J1/J2 indicate where direct alignment to main board pads would be.
Having said all that, IMHO, surface mount parts provide the ideal solution. Produces the smallest board, cleanest, shortest copper tracks, with multiple mounting hole options.
Here's the "X-ray" views showing copper traces. Thru-hole far more complex than SMD (1206 size SMT shown)..
Thru-hole:
SMD:
HalfApt
Well-Known Member
What main board version? My examples are for v3. v2 would require some changes, notably a longer board, as the main board pads are inset further than v3.
I don't think I have any v2.xx left, all should be v3.x Some are the red version.
Athanasios
AvFan
Super Member
I noticed it was cantilevered so maybe the switch board can be widened enough to provide four mounting holes beyond the width of the V3.2 board. The width of the switch board isn't a big deal for me but it may be for others. I like the idea of pins from the new board that slide into the loading holes on the V3.2 board. If additional mounting holes aren't an option at least those pins could be soldered and provide some support. Extending the switch board beyond the narrow edge of the V3.2 board is also fine to me but others might not like loosing the direct connection to the holes on the V3.2 board.
I know the traces using through holes are more complex but it would be easier for me to swap out in the future a resistor or capacitor should I want to change things up later. I'm going to use a numbered (1, 2, 3 etc) switch faceplate versus the actual load value to provide future flexibility.
I just looked at Digi-Key and they don't have any of these switches either. That could be the biggest issue to be resolved before this idea could be implemented.
Thanks again!
HalfApt
Well-Known Member
Only the ADJUSTABLE versions are non-stock. Mouser has the fixed-stop in-stock.
This should work for both you and Athanasios. If you don't need the extra 4 mounting holes, just cut the ears off at the white lines. Connectors align w/main board load resistor holes.
That's as far as I can go without more specific details about what you may want.
HalfApt
Well-Known Member
No, you can use as many as you need, but you must use an equal number of resistors per channel on the resistor switch, and an equal number per channel on the cap switch.
The biggest problem is finding a switch in-stock somewhere that has limit stops at the number of positions you want.
These switches are made in both 10 and 12 position. Either can be used on the board.
Both types are made with the full range of positions (10/12), AND with fixed stops at 8,6,4 & 2 positions, OR with user adjustable stops...IF...you can find them in-stock anywhere.
You DO NOT want to leave any positions without a resistor, otherwise the load could accidentally go open circuit, which is bad.
OTOH, if all you need is 6 load positions (for cap or resistor) these switches are overkill at 3x the cost of a simple 2P6T switch
HalfApt
Well-Known Member
They are back in-stock, only 16 available at the moment, more expected this month.
https://www.mouser.com/ProductDetail/Grayhill/71ADF30-02PAJS?qs=ls7QRyWmRk6pzKZ1wi65ww==
You have shaft choices to consider (above is 1/8"):
- 71A model: 1/8" shaft
- 71B model: 1/4" shaft
- 71E model: 4mm shaft (0.157" @ 5/32")
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audi0n00b
Active Member
Looking for 1
AvFan
Super Member
That is perfect for me and hopefully for others thinking about implementing a load switch. What would be the next steps to get the board produced? Since I started all this I'm in for any setup costs etc.
AvFan
Super Member
HalfApt
Well-Known Member
If everything looks good, no further changes or features, I can finish up and post the gerber files for download.
Gerber files are needed at China shops, for lowest cost.
And/or I can post to OSHPark (USA) for direct order. $27.90 for 3 boards ($9.30 per board), shipped.
If going thru China, you might want to co-ordinate with the others who want boards, and get a total to order.
HalfApt
Well-Known Member
50mm
AvFan
Super Member
OK, let's see if we can figure out if any folks are interested and how many of these switch boards they'd like.
I'm in for three boards.
Next?