I still don't know... part of me wants to say:

• Bah, just go through with it. You've got the PCB already, and more than enough money kicking around. At the end of it you'd have a pretty decent amp that (if you make the enclosure correctly) will be fairly portable, and you'll have learnt a fair bit by the experience.
  

and another part of me wants to say:

• Whatever, just build a Noisy Cricket for the sake of having an amp. It will be easier, cheaper and you'll have the tools to make it a lot cheaper to come back to this project at a later date. With a decent pair of drivers (which you have) it should sound quite good and will be far more portable.
  

I just don't know which one is right...

By that measure i shouldn't really factor in delivery either so 40+15 brings it to £55. Which is okay, i guess. It's just that it's all very well not factoring in these costs for the sake of comparison but i've still got to pay them. The soldering iron would probably pay for itself mind you, the amount of things i've broken and said 'i need to buy a soldering iron' for... i digress, if i can salvage a bit more wood then i shouldn't have to spend so much on the enclosure, say £60 in total? I dunno, i'm at two ends about it now.

Doing a quick list compilation (as you do) it looks like making that Tube Cricket would be more expensive than continuing with this. And there are a lot of things i don't understand about Valves just yet... or indeed betray the forum  8|

I was going to go for a wooden case.These are all at Rapid where possible. Price is 'each' and i've listed below where there is more than one.

---

• 0.25W 5% Carbon Film Resistor 100 pack - £0.50 (0.5W is twice as much)
  I count 8 of these so £4
• 500k Miniature Carbon Preset Pot, Lin, 30% tolerance, 0.03W rated - £0.08
• 10k Rotary Carbon Pot, Log, 0.1W - £0.80
• 4u7 50V Low Impedance Radial Electrolytic Capacitor - £0.05
  Sheet sais 6 of these but i could get 10 for exactly the same price of £0.30 (they're £0.03 if you buy 10 or more)
• 100pF Ceramic Disk Capacitor - £0.01
• 100nF Ceramic Disk Capacitor - £0.02
  3 of these so £0.06
• 470pF Cermic Disk Capacitor - £0.01
• 2200u 25V Axial Electrolytic Capacitor - £0.59
  2 so £1.18
• 4.7v 500mW Zener Diode - £0.02
• 1N5408 Rectifier Diode - £0.07
  2 so £0.14
• 5mm Green Recessed Chrome LED - £0.87
  Just thought i'd treat myself to a fancy one
• GBU8J SIL Bridge Rectifier 8A 600V - £0.44
  Going by as much 'overkill' on that one as possible.
• Preamps i'm not to sure about, TL071 is £0.26, a TL081 is £0.34 and there's one called a TL081CD for £0.20. What would be better?
• TDA2050V - £2.27
• 6.35mm Mono PCB Mounting Jack Socket (2 switched)- £0.33
• 3.5mm Stereo PCB Socket  (2 switched) - £0.10
• Subminiature Omni Directional Electret Microphone Insert - £0.50
  Do i need solder pad or PCB mounting?
• SPST High Current Toggle Switch - £0.99
• 100mA 20mm Slow Blow Fuse - £0.15
• Chassis Mains Transformer 50VA 0-15V 0-15V - £9.15
  Would that be okay? Just that other site turned out to be wholesale...
• EPE PCB 336 - £5.47
• 8 pin DIL Socket - £0.14
• 20mm panel mounted fuseholder - £0.27
• Black Pointer Knob - £0.28
• 11x2m Stranded Equipment Wire - £1.25
• 13A Standard Mains Plug - £1.10
• 3-Core 13A Mains Cable - £1.69/m
  Say 3m? £5.07.
  

---

I make that to be £35.32. Which is fair enough, £10 more than in 2002. Add onto that VAT (keep forgetting to show it on that site) and it's roughly £42. Delivery at two separate places is £4.95 and £2.99 making the total £50. Then i'll need a new soldering iron and solder, so that's £15 (for a 30W Antex) bringing it to £65. The Celestion Super 8 is £13.23 with £6 delivery so lets say £20 bringing the total to £85. The enclosure will probably cost at least another £20, which is a bit much for me really at the minute. £85 is the price of a Peavy VYPR 15w, which will be a hell of a lot better than this however you look at it. Hence i'm still thinking about just making a Noisy Cricket (which i make to be about £35 total including soldering iron) or something for the time being, i'd come back to it since i've got the PCB already and i would have the tools already. Not only that but i've been playing without an amp and i've kinda got used to it.

Incidentally, i found this:

http://www.diystompboxes.com/smfforum/index.php?topic=66623.0

Okay, well evaluating the whole cost of it i think i'm going to have to put this project on the backburner for a bit and do what i probably should have done to begin with an make a Noisy Cricket.

I've got two old computer speaker drivers here, 4 Ohm 3W with a 70mm diameter. I assume they'd be up for the job? Would they be in series or parallel? Is it a choice between a speaker or the output jack? I could make two i guess, one with speakers and one to feed into a cab... one thing that's been bugging me about this is that in a 'sealed' enclosure, what is the earth? Is it just a bit of aluminium or something? Is there a way of working out how big it has to be? And the Radioshack wiring diagram doesn't show anything connecting to the earth, but the circuit diagram clearly shows 11 different ones. Thanks.

Again, sorry for the large number of newbie questions. Don't know who else to ask...

I haven't pressed 'buy' yet, i smell something amiss somewhere... £80 is about $125 by today's exchange rate, but that's including tax. I found a 1N5408, will that be aright? I was talking about the in-line bridge rectifier though, not the diode but thanks for the catch.

Sorry about the large images, just me being lazy.

www.rapidonline.com:



www.maplin.co.uk:


cpc.farnell.com:

EDIT: Replaced with thumbnails, probably a good idea.

Okay, i've managed to source pretty much everything apart from two, being the BZY88 4v7 Zener Diode and a 2A 100V in-line bridge rectifier. For the latter i can find either a 2A 200V one or a 3A 100V, which would be better? As for the Zener Diode... does it even exist? I can't find it anywhere, is there something that would work in its place?

Comes to about £80 now for all the innards and speaker, not including enclosure or PCB. That is with a new soldering iron but does that not strike you as a bit much? I mean, i could get a Peavey Vypyr 15 for £85 which would probably be cheaper than the total project cost.

Okay, thanks for your help - you learn by making mistakes so i'm just going to go for it. Little update - PCB arrived today, i love how the dog only seems to destroy the non important mail.



Again, sorry for the image quality. I would have used a better camera but i'm having problems with ISO and the flash casting shadows of the lens. Anyway, looks good. Home etched as far as i can tell, as you would expect. Not the most pleasing of colours but that doesn't really matter. It's smaller than i thought it would be, which will help with the plan i've got to make a small, portable enclosure.

Quote from: J M Fahey on April 03, 2010, 04:33:06 PM
Tha heatsink will do.
You can't replace TL081 with TL082 but with TL071.

Yeah, i wondered because one sais 'dual' and the other 'mono' in their descriptions. Kinda being newbie here and assuming that a higher number is better but which of the two (81/71) would be better? Thanks

Oh, and i'm having a bit of trouble finding a 470k Carbon Preset Potentiometer, could i replace it with say a 500k one? Sorry to be such a pain...

Okay, so replace the TDA2030 with a TDA2050 and the TL081 with a TL082. Anything else i should know?

I've got a heatsink here, pulled it from an old PSU. Was cooling a few similar looking chips, but i think it would be okay for the 2050? Roughly 3cmx3cm on one side, 5cmx3cm on another and 4cmx3cm on the oposite one. Not counting the fins. Nearly 2mm thick and aluminium as far as i can tell.



Sorry for the quality, phone camera doesn't do macro very well.

Quote from: tonyharker on April 02, 2010, 01:37:01 PM

Quote from: E on April 02, 2010, 08:29:41 AM
i made a copy of the PDF without the giant 'www.epmag.com' in the middle of every page so you can actually see the diagrams.

So How did you do that then? Huh!!

Tony.

Open original PDF
Print to file - PDF (gets rid of the permissions)
Open with PDF Editor (Linux)
Select watermark
Press delete
Repeat for every page
Save
Host



Oh, and will using a 12v transformer instead of a 9v one work?

That's great, thanks. Since i've got two weeks off i'll probably have a go at it... if anybody's interested i made a copy of the PDF without the giant 'www.epmag.com' in the middle of every page so you can actually see the diagrams.

http://www.mediafire.com/?mmmvn4rft2k

Home etched PCBs are great, but they can take a lot of time and indeed money. You could also use perfboard, which done well can be almost as good (and it doesn't make a difference to the finished product) or even wire wrapping (i think it has a better name, just can't think of it at the moment), which can actually be used as a permanent solution while still allowing you to quickly fix any mistakes.

http://www.stevechamberlin.com/cpu/about/

But yeah, if you use perfboard or PCB then it's usually an idea to try it out on a breadboard first. Not entirely sure how to lay it out, i could do with a bit of help in that area too.

Well keep us posted.

Would using solid capacitors have any effect?

Quote from: rowdy_riemer on March 08, 2010, 10:28:30 AM
Maybe you should check out the Nelson Pass's "Zen" amplifier. www.passdiy.com/pdf/zenamp.pdf. You might can bridge a couple of these for 40 watts.

www.passdiy.com/pdf/retofzen.pdf

Some 'improvements' in there. I'm interested to see how this turns out actually, what would you use for a preamp?

I'd strongly recommend learning it. Not necessarily to an advanced level, just the basics would suffice. You could get one of your friends to help you with fingering and stuff, and use this great resource for doing stuff in your own time:

http://www.justinguitar.com/