Transistor equivalent

I nearly posted a photo of the large chested rock singer called Ally.
Brits say and spell "aluminium" differently to us (we call it aluminum) so I guess they can abbreviate it to anything they want.

How can I make mould for other casting method? Wood will burn, even it was soaked in water, steam will cause air bubbles in both surface and inside of the heatsink. I am scared by air bubbles in the surface because transistors will not contact fully (cause overheat).

audioguru said:

I nearly posted a photo of the large chested rock singer called Ally.
Brits say and spell "aluminium" differently to us (we call it aluminum) so I guess they can abbreviate it to anything they want.

Click to expand...

Is that a female type singer? - if so post otherwise- don't post

Yeah we all do things differently- especially me

Oh, Happy new year to all of you.

Nikolai Petrenko said:

How can I make mould for other casting method? Wood will burn, even it was soaked in water, steam will cause air bubbles in both surface and inside of the heatsink. I am scared by air bubbles in the surface because transistors will not contact fully (cause overheat).

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Yes, I can see now that wood would be no good, and wet wood even worse. Do you think you can cast the design I have posted, using lost foam. I can't see how.
Only three things count though with the back panel/ heatsink
(1) Will it be strong enough.
(2) Will it crack
(3) Will it be flat enough and thick enough under the six power transistors?

Nikolai Petrenko said:

Oh, Happy new year to all of you.

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Same to you my friend

spec said:

Yes, I can see now that wood would be no good, and wet wood even worse. Do you think you can cast the design I have posted, using lost foam. I can't see how.
Only three things count though with the back panel/ heatsink
(1) Will it be strong enough.
(2) Will it crack
(3) Will it be flat enough and thick enough under the six power transistors?

Click to expand...

Thank for your carefully. I say I can unless I'm not lucky .
(1) Yes, will strong, alum is a ductile metal unless dross stay inside or air bubbles.
(2) Crack? No, it also cause by ductility. But crack can appear when alum didn't fill the mould fully, wet sand.....
(3) Flat? Yes. You can see this video: . The sand must be pressed to strong enough that will not fall down when styrofoam evaporate. Sand must be fine; clean from dirty like grass, stone, chips of plastic or glass, and even **** (don't think me like a nasty guy)...
With a long and very big heatsink, I can't trust that sand will not fall down, so I think sand should be added some fine powder like plaster or white cements for two reasons:
+) Fine powders will act like a binder to reinforce sand not to fall down (fine powder pretty sticky)
+) Fine powders also fill small gap between sand grains so the heatsink will be more smooth

Questions: Mounting holes for TO-220 like packages? Room for screw heads? Mill off later? Tapped set-screw could also be used if it could fit between fins?

KeepItSimpleStupid said:

Questions: Mounting holes for TO-220 like packages? Room for screw heads? Mill off later? Tapped set-screw could also be used if it could fit between fins?

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Yes.

Nikolai Petrenko said:

Thank for your carefully. I say I can unless I'm not lucky .
(1) Yes, will strong, alum is a ductile metal unless dross stay inside or air bubbles.
(2) Crack? No, it also cause by ductility. But crack can appear when alum didn't fill the mould fully, wet sand.....
(3) Flat? Yes. You can see this video: . The sand must be pressed to strong enough that will not fall down when styrofoam evaporate. Sand must be fine; clean from dirty like grass, stone, chips of plastic or glass, and even **** (don't think me like a nasty guy)...
With a long and very big heatsink, I can't trust that sand will not fall down, so I think sand should be added some fine powder like plaster or white cements for two reasons:
+) Fine powders will act like a binder to reinforce sand not to fall down (fine powder pretty sticky)
+) Fine powders also fill small gap between sand grains so the heatsink will be more smooth

Click to expand...

Hey Nikolai,

You are a smart dude... I am amazed and have learned a lot from your post; can't wait to start casting ally, myself.

I had no idea the casting was so clean and accurate. I imagined some blood and thunder procedure with smoke, flames, and general mayhem. I also expected the cast item to be rough with flashings all over the place. After seeing the video I can find no reason why your back panel should not be a Rolls Royce job.

Adding binder, as you say, would seem to me to be a very good move.

Thanks a lot for the heads up on casting ally- I am collecting soda cans already

UPDATE

In view of what I have learned from you about casting, I can see no reason for the rear panel on the rear panel/heatsink (if you folow me). I will thus, re draw the rear panel taking the new information into account. The dimension of the rear panel and general layout will be the same though. How thin could you make the fins. I think 2.5 mm would be about right. Would you be happy with that?

Nikolai Petrenko said:

Yes.

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Hi Keep, good observation. The policy I am going for is drill and tap rather than nut and bolt which I hate. I'm hoping the panel, where the output power transistors mount, will be 3mm or more thick which should give plenty of meat for tapping a thread.

Unless TO-3 cans are used, the plastic cased trans will have a bar going across the case in the middle, with two clamping screws, to ensure good thermal conductivity, especially long term. Plastic paks are badly designed, badly made, and make me ill every time I see them, but they are cheap and easy to use.

Nikolai's project is getting really interesting now- I smell success in the air.

ERRATA
(1) Arrow should point to hole

ERRATA
(1) Possible design change: bass sub amp and left amp swap positions

NOTES
(1) Phone and mains switching circuits not shown.
(2) The case has 4 x 12 mm approx thick compliant (rubber etc) feet on the bottom
(3) The amplifier boards are mounted approximately 25 mm up from the lower edge of the Back Panel
(4) The left and right panels are wood; hardwood is best: Oak, Walnut, Teak, Rosewood etc
(5) The inner faces of the left and right panels are clad in thin sheet ally (glued with epoxy adhesive or other suitable adhesive)
(6) The entire verticle length of the side panel conductive cladding to be electrically bonded to front and rear panels
(7) Star Point 1 (SP 1) is formed on the back panel near to the IEC mains connector by a tag bolted to the rear panel.
(8) The live and neutral leads from the IEC connector are tightly twisted together and wrapped with at least two layers of aluminium foil, which is held in place by tape. A wire is taped in contact with the foil near the IEC connector. This wire connects to SP1.
(9) The mains cabling from the IEC connector imediately bends vertically and enters the case via an open hole top left in the rear panel inner panel.
(10) The aluminium clad mains cable, is cleated firmly along the inner top of the left cheek.
(11) Four screw heads on front panel are hidden by decorative buttons, of user's choice, glued in place
(12) Wiring from rear sub panel passes through holes in the heatsink and is routed under the amps.

NOTES
(1) in general additonal electronics would be in a can near to front panel right
(2) For best results a dedicated phone amp should be used

ERRATA
(1) Bass sub terminals should be shown to right of centre of sub panel

Thanks. I have learnt in practice, not in any books. I am also learning a lot from you and other members.
450mm to big ( but I didn't it isn't well). At least 3kg alum must be collected because you know may be 1/5 of them will be oxidized to alum oxide float in the surface of liquid alum with other dirty... Magnesium also very easy to burn when melting. To contain those metals, I think the crucible should be a steel canister like Ensure 400g canister...
I think clay powder is better than sand because they will become very sticky and strong after I squeeze they firmly. Clay also much more smooth than sand. But clay must be heated to burn any organic thing and water.
Alum wrap inside the cabinet and over the power supply wires are prevent amp from hum in air and magnetic field around power wires?

Nikolai Petrenko said:

Alum wrap inside the cabinet and over the power supply wires are prevent amp from hum in air and magnetic field around power wires?

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Hum in air = electrostatic fields: yes to protect from them but not electromagnetic fields. You would need magnetic material for that, like transformer core material: Muemetal is best.

Also for safety: ally sheet is connected to rear and front panel, which is earthed.

Also general good practice.

Nikolai Petrenko said:

Thanks. I have learnt in practice, not in any books. I am also learning a lot from you and other members.

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That's OK but no' like' votes for all the work I do for you?

Nikolai Petrenko said:

450mm to big ( but I didn't it isn't well). At least 3kg alum must be collected because you know may be 1/5 of them will be oxidized to alum oxide float in the surface of liquid alum with other dirty... Magnesium also very easy to burn when melting. To contain those metals, I think the crucible should be a steel canister like Ensure 400g canister...
I think clay powder is better than sand because they will become very sticky and strong after I squeeze they firmly. Clay also much more smooth than sand. But clay must be heated to burn any organic thing and water.

Click to expand...

Are you saying the rear panel is big but you can handle it. Clay sounds good- along the lines I was thinking of. But can't you mix some builders cement and add a plasticiser to the fine sand to make the mixture smoother and easier to work with. Washing up liquid can be used at a push, but not the ideal.