Electronics - Amplifier kits?

Lakeland · 18 Dec 2010 at 21:45

Electronics - Amplifier kits for £1 ?

I'm looking to see how feasible it is to have students build an audio amplifier for their Y9 electronics lesson in the hope that it will engage and hopefully get more of them interested in electronics.

There are two packs available on Rapid electronics:
Class pack 1 - This one works out at £2.82 per student which is too expensive as I only have an allocation of £2 max per student and I'd like to look into enclosures too.
Class pack 2 - This one works out at £1.79 per student which is better but still doesn't leave much left over.

Is there anything else out there other than what Rapid offer?

2bit · 18 Dec 2010 at 22:01

Hmm - tricky one.

My initial thought would be to introduce your students to the delights of Veroboard (stripboard) and just buy the components separately - but that's probably a lot more effort and may mot be cheaper in the long run.

At £1.79 I have to say it's not bad value - plus you get teaching material included (if that's applicable).

I guess you also need to factor in the price of the batteries too?

A[L]C · 18 Dec 2010 at 22:10

Why not drop them a mail, explain the situation and see what they say. If you dont ask, you dont get.

Lakeland · 18 Dec 2010 at 22:25

I could copy the PCB and make them in house, a board would cost £4 and I'd get about 10 from a board, that would be 40p per board.

IC - 31.7p
Jack socket - 5p
Jack x2 - 18p
Speaker - 44p

That comes to £1.38 for the major components, the rest should be doable for another 20p so £1.58 total, seems like a lot of work for a 20p saving. Is it possible to get speakers for less than 44p?

We've got an account with Rapid, I will give them a call to see if there is any movement on the price. It's a big ask to build an audio amplifier for £1!

Edit, just thought, I could hard wire the audio cable and scrap the jack socket and one jack, that would take 14p off the total so £1.44

2bit · 18 Dec 2010 at 22:39

Sounds like a good plan if you knock the PCBs up yourself.

What would you hard wire the amp to? Surely your students would want to plug their phones /iPods etc. into them - that's the payback for making it and making it correctly?

You could scrap the LED and even the on/off switch - but not the jack I'd say.

MikeHunt79 · 18 Dec 2010 at 22:42

£2 is such a low limit, but it does present an interesting challenge.

Remember with companies like rapid the higher quantity you buy the cheaper each item is. Also check out farnell, sometimes they price EOL stuff really cheap, I was buying bags of 100 metal film resistors for less than £1...

2bit · 18 Dec 2010 at 22:49

MikeHunt79 said:
£2 is such a low limit, but it does present an interesting challenge.

Remember with companies like rapid the higher quantity you buy the cheaper each item is. Also check out farnell, sometimes they price EOL stuff really cheap, I was buying bags of 100 metal film resistors for less than £1...

I guess he doesn't have huge numbers of students so price breaks from suppliers would be tough.
The Rapid Electronics kits are obviously aimed squarely at the education market with their particular budgetary restrictions.

Lakeland · 18 Dec 2010 at 22:50

2bit said:
Sounds like a good plan if you knock the PCBs up yourself.

What would you hard wire the amp to? Surely your students would want to plug their phones /iPods etc. into them - that's the payback for making it and making it correctly?

You could scrap the LED and even the on/off switch - but not the jack I'd say.

Was thinking about scraping one jack but leaving the other at the end of the wire so it can be plugged into ipod/walkman etc.

Batteries can be provided to test the circuit and we can pass them on at cost (50p) to students if they don't have one at home to use.

I'm wondering if some really basic npn transistor circuit would be sufficient :confused:

2bit · 18 Dec 2010 at 22:58

Lakeland said:
Was thinking about scraping one jack but leaving the other at the end of the wire so it can be plugged into ipod/walkman etc.

Batteries can be provided to test the circuit and we can pass them on at cost (50p) to students if they don't have one at home to use.

I'm wondering if some really basic npn transistor circuit would be sufficient

Yeah the basic transistor circuit is an idea but again I'm not sure it saves you money. 31p for an audio amp is pretty good (in small quantities). A few discrete transistors may work out just as expensive if not more costly - plus they are delicate. Good if you want to get into how the amplifier actually works from basics - but maybe not what you're looking for. The IC's are fairly hardy.