Dumbleator Build Questions

[donvan]

1)What are people using for eyelet board material? I bought some predrilled boards from a Amplified Nation when I built my #183 amp. I would love to find a source for blanks of that type of material. It looked like fiberglass or perhaps blank PCB board.

2)Any recommendations for a chassis/box? I'm using a small Hammond 262A12 transformer so I can use a narrow 1RU size box but I'm not necessarily trying to build a small or mini version.

Suggestions are appreciated!
Don

[erwin_ve]

Hi Don,
you can make eyelet boards with FR4 material.
It is epoxy/glass fibre based and you need protection for both hands and breathing while drilling/sawing. I used to make them myself and without protection the glass fibre itched for months after.

Erwin

[xtian]

Here's where I get my FR4:

https://www.mcmaster.com/products/fr4-b ... -and-bars/

[donvan]

Thanks erwin and xtian!
I see that there are many different thicknesses to choose from. Which do you use?

[martin manning]

I vote 1/16" thickness, and eyelets with 0.090 length.

[xtian]

1/16" is flimsy and too flexible for full-sized boards--ok for bias boards, for example. I prefer 1/8" thickness.

[mensur87]

Use FR4 for the eyelet board. Go with 1/8" thickness for full-sized builds, 1/16" is too flimsy. For the chassis, check Hammond; they have sizes that fit your transformer.

[martin manning]

I bought some predrilled boards from a Amplified Nation when I built my #183 amp. I would love to find a source for blanks of that type of material. It looked like fiberglass or perhaps blank PCB board.

If I'm not mistaken, those boards are 1/16" G-10/FR4. Do you see them as being "flimsy?" Doubling the thickness means doubling the quantity of hazardous dust and doubling the wear on your tools.

[erwin_ve]

For a Dumblelator 1/16" (2mm) is more than suitable. Those Dumblelator boards are small compared to a full size ods board. If you are worried about flimsy boards with 1/16": add a mounting point where you think the board will flex or put a extra insulator board(same size underneath. Fwiw I used 1.5mm on all boards in my 20+ builds(except the power filtering board: 2mm) and never experienced any problems.

Erwin

[donvan]

I bought some predrilled boards from a Amplified Nation when I built my #183 amp. I would love to find a source for blanks of that type of material. It looked like fiberglass or perhaps blank PCB board.

If I'm not mistaken, those boards are 1/16" G-10/FR4. Do you see them as being "flimsy?" Doubling the thickness means doubling the quantity of hazardous dust and doubling the wear on your tools.

Good point. Yes, I was happy with the thickness of those boards.

[donvan]

Regarding the chassis, I don't recall anyone ever talking about ventilation. Are vent holes in the chassis needed so that heat from the tube can be dissipated or is heat not an issue with this circuit?

[martin manning]

Heaters in one 12AX7 produce less than 2W, and the plates only add another 0.5W. If the enclosure is a 1U half rack I don't think you will need any ventilation.

[donvan]

If I don't plan to use it as a mute switch, is the standby switch really needed? For the power supply, I am using 500v capacitors. Just wondering what your opinions are.

[martin manning]

Not needed.

[M Fowler]

I use fr4 1/8 because 1/16 is to flimsy for me.

Mark