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Cooking up a PCB

I have used a cheap oven to reflow solder before, but I was curious if I could use a simple hotplate to attach annoyingly small SMD components to a simple PCB.

Despite the appalling application of solder paste it seemed to work OK!

I do not store my solder paste in a fridge, but full disclosure I do live in a fridge known as Tasmania, so the paste did what it was supposed to do after some heat tickling.

A proper person would do the whole solder temperature ramp profile adherence - but this was a quick and dirty test of the temp rating of the hotplate and also a "proof of concept" experiment should I wish to take this method any further.

If you are looking to do SMD soldering the easy way, including ham-fisted solder paste application - check out this video!

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Mailbag #21

Lovely packages arriving in "downtown Tasmania" including some laser modules. Or as my finance minister says "Why?!"

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A commercial Solar Light

I was clumping through a common staff area the other day and spotted a solar light (with a PIR) for sale through some charity. 

The packet claimed that the unit didn't need electricity, batteries or wires! Free energy?? 

It was only $12 (a great deal cheaper than similar units found in the shops) and I was intrigued to find out what was inside. I suspected that a battery was in there, and I was hoping for a QX5252 based (or similar) circuit whereby I could point and say "Oh, I understand that!"

It was not "to be (or not to be)" as the video below shows - there were surprises...

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D2822 1W Amplifier

There's an IC called a TDA2822 typically rated to drive speakers at around 3W. It's been around so long that on many sites it is listed as obsolete!

It's even used in a few cheap amplifiers available online for very few dollars.

Nonetheless, there is also a facsimile of the chip (I think) to be found called the D2822. It has a separate but similar datasheet - topping out around 1W and also touted for headphones and similar cheap amplifier applications. The pinouts for both chips seem to be the same.

I used the circuit shown in the datasheet and the pinout given as well to make an audio amplifier as follows.

At first I tried rubbish little speakers which were suitably horrible, but then I grabbed a couple of recycled speakers and the sound was actually quite remarkable coming from a tiny little 8-pin "obsolete" chip that barely gets warm as it cranks out the phat beats.

The video is a little loud in places (sorry!) as I have a new phone and keep hitting "volume up" instead of  "volume down" and vice versa!