Electronics? (transistors, capacitors, soldering and all that jazz)

cornbb

Hey guys, just wondering if this forum is suitable for discussing electronics as supposed to electrics? If you know what I mean. I'm almost a complete novice at building circuits but I hope to start a big project soon, as with everything else in life I'll be turning to boards for help, just wondering if this will be the best place to do it

This is the project in question in case anyone is interested: http://www.musicfromouterspace.com/analogsynth/SOUNDLABMINISYNTH/soundlab.html

RoundyMooney

Please do

cornbb

Ok, you asked for it!

Some questions before I even start off:
- Am I mad taking this project on without having had experience in electronics since secondary school? I intend to buy some sort of beginners set on which to cut my teeth with a soldering iron before launching into the main kit.
- Will my cheapo 25w soldering iron do or should I really get something fancier?
- Can buy the premade PCB but will need to source the rest of the components elsewhere. Is Maplin a good bet or should I look elsewhere? I don't want to break the bank.
- What other equipment/tools are necessary?
- Any other invaluable tips for a soldering noob?

I will inevitably be back with more questions.
Thanks guys!

DublinDilbert

cornbb wrote: »

Ok, you asked for it!

Some questions before I even start off:
- Am I mad taking this project on without having had experience in electronics since secondary school? I intend to buy some sort of beginners set on which to cut my teeth with a soldering iron before launching into the main kit.

Nope your not mad, its not going to cost the earth to have a mess around with it... maplin do some cheap kits with all the parts included if your looking for something to mess around with.

There's a cool book called the art of electronics if your looking for something to read, its full of little circuits.. also the internet has no shortage of stuff too.
http://www.amazon.co.uk/Art-Electronics-Paul-Horowitz/dp/0521370957

cornbb wrote: »

- Will my cheapo 25w soldering iron do or should I really get something fancier?

Try get one with a fine tip on it. Alot of the cheaper ones are really meant for soldering wires etc, not PCBs. Some of the 240V Antex ones are ok, just get a smallish tip on it.

Get a solder sucker + solder wick, and mess around with a few old PCBs, soldering and desoldering components... all u need to do is practice.

cornbb wrote: »

- Can buy the premade PCB but will need to source the rest of the components elsewhere. Is Maplin a good bet or should I look elsewhere? I don't want to break the bank.

Its a big enough project, maybe try do one of the small ones from maplin first... i'd buy the PCB, and try source the compents locally... maplin do some cheap through hole resistor kids all the values you should need.... they also have some capacitor kits too....

you may need to goto radionics too for some of the other stuff.... still cant' see it costing the earth.

cornbb wrote: »

- What other equipment/tools are necessary?
- Any other invaluable tips for a soldering noob?

I messed around building circuits for years, some worked some didn't work.... if i was doing anything sound related i'd get 2 things:-
1) A simple oscilator / signal generator to act as a source for testing. you should be able to get a kit in maplin to this, maybe it would be an ideal first project??
2) A cheap oscilliscope so you can see whats happening, where your signal is or isn't reaching in the circuit. Maplin do a velman scop for about €100, which would be idea.

10-10-20

I'm currently building circuits, so would be delighted to assist where possible.
The project above is simple in terms of the fact that it's only assembly. Patience and a fine soldering bit will see you through it.
Every time you seat a component on the board, check and double-check the orientation and reference/location. Then solder.
Maybe consider putting IC holders on the PCB first so that if you do make any mistakes, it's easier to recover from!

cornbb

DublinDilbert wrote: »

Nope your not mad, its not going to cost the earth to have a mess around with it... maplin do some cheap kits with all the parts included if your looking for something to mess around with.

There's a cool book called the art of electronics if your looking for something to read, its full of little circuits.. also the internet has no shortage of stuff too.
http://www.amazon.co.uk/Art-Electronics-Paul-Horowitz/dp/0521370957



Try get one with a fine tip on it. Alot of the cheaper ones are really meant for soldering wires etc, not PCBs. Some of the 240V Antex ones are ok, just get a smallish tip on it.

Get a solder sucker + solder wick, and mess around with a few old PCBs, soldering and desoldering components... all u need to do is practice.




Its a big enough project, maybe try do one of the small ones from maplin first... i'd buy the PCB, and try source the compents locally... maplin do some cheap through hole resistor kids all the values you should need.... they also have some capacitor kits too....

you may need to goto radionics too for some of the other stuff.... still cant' see it costing the earth.



I messed around building circuits for years, some worked some didn't work.... if i was doing anything sound related i'd get 2 things:-
1) A simple oscilator / signal generator to act as a source for testing. you should be able to get a kit in maplin to this, maybe it would be an ideal first project??
2) A cheap oscilliscope so you can see whats happening, where your signal is or isn't reaching in the circuit. Maplin do a velman scop for about €100, which would be idea.

10-10-20 wrote: »

I'm currently building circuits, so would be delighted to assist where possible.
The project above is simple in terms of the fact that it's only assembly. Patience and a fine soldering bit will see you through it.
Every time you seat a component on the board, check and double-check the orientation and reference/location. Then solder.
Maybe consider putting IC holders on the PCB first so that if you do make any mistakes, it's easier to recover from!

Sweet, well thanks for the help guys. I just popped out to Maplin and bought some tools and a signal generator kit, sounds pretty apt given what I'll be building later on. Also got a multimeter, which I'm sure I'll have some questions about later... I can't afford an oscilloscope right now but I hope to put together a software oscilloscope at some point, i.e. a simple circuit which will plug into my soundcard and check signals with suitable software.

I'm gonna get cracking at this now...

DublinDilbert

cornbb wrote: »

Sweet, well thanks for the help guys. I just popped out to Maplin and bought some tools and a signal generator kit, sounds pretty apt given what I'll be building later on. Also got a multimeter, which I'm sure I'll have some questions about later... I can't afford an oscilloscope right now but I hope to put together a software oscilloscope at some point, i.e. a simple circuit which will plug into my soundcard and check signals with suitable software.

I'm gonna get cracking at this now...

That a sounds like a very good starting point....

Never thought about a PC sound card based scope, no shortage of s/w out there to do this. You could make up a simple protection device with some series resistors and some zener diodes so you don't blow up your sound card. You won't be able to measure DC on this, but should do for alot of audio stuff.

Also i'm sure you could pick up an old PC ( say a 1GHz machine) with sound card and just use that as a scope, so if it gets damaged who cares...

cornbb

Right, I finished building one of those Maplin kits last night - a simple signal generator with fixed 1kHz fequency and 4 different waveform selectable with a jumper - http://www.maplin.co.uk/module.aspx?ModuleNo=22553&doy=11m1

Now, more questions:
- The kit worked reasonably well when I finished but I could hear a faint buzzing even when no waveform was selected (i.e. when the jumper was removed). Any idea how this could be debugged?
- My multimeter has various modes for measuring resistance, which one should I use for testing resistors, looking for short circuits etc? Sometimes its doing nothing at all, even when I touch the probes together (should show zero resistance, right?) Am I doing something wrong or could there be a fault with the multimeter?
- The soldering went reasonably well, however as the night progressed the iron started "spitting" bits of smoky solder although I tried to keep it clean and tinned. Do I need to get some sort of solder cleaner/flux? I was under the impression that solder has a flux core, maybe not in my case. Should I get eye protection in case a gob of solder finds its way in there? Any other tips for cleaning/preparing my components, PCB and soldering iron tip?

cornbb

DublinDilbert wrote: »

That a sounds like a very good starting point....

Never thought about a PC sound card based scope, no shortage of s/w out there to do this. You could make up a simple protection device with some series resistors and some zener diodes so you don't blow up your sound card. You won't be able to measure DC on this, but should do for alot of audio stuff.

Also i'm sure you could pick up an old PC ( say a 1GHz machine) with sound card and just use that as a scope, so if it gets damaged who cares...

I found this: http://www.ladyada.net/library/equipt/diyaudioprobe.html so that might be my next project.

I've got a decent soundcard with a gain control for the input, does that lessen my chance of blowing things up?

10-10-20

cornbb wrote: »

I've got a decent soundcard with a gain control for the input, does that lessen my chance of blowing things up?

Hmmm - It may confuse matters as you will have to establish a starting point for calibration of the voltages. If possible, set the gain to 1:1 and calibrate, then make sure you remember if you move the gain adjuster at all as your readings will be out.

cornbb

10-10-20 wrote: »

Hmmm - It may confuse matters as you will have to establish a starting point for calibration of the voltages. If possible, set the gain to 1:1 and calibrate, then make sure you remember if you move the gain adjuster at all as your readings will be out.

Are voltages/gain/amplitude all that important though? It might be handy to check voltages at some point but I'll mostly be focusing on checking frequencies and examining waveforms.

10-10-20

cornbb wrote: »

Right, I finished building one of those Maplin kits last night - a simple signal generator with fixed 1kHz fequency and 4 different waveform selectable with a jumper - http://www.maplin.co.uk/module.aspx?ModuleNo=22553&doy=11m1

Now, more questions:
- The kit worked reasonably well when I finished but I could hear a faint buzzing even when no waveform was selected (i.e. when the jumper was removed). Any idea how this could be debugged?

Without knowing the circuit, I'd guess that it could be possible that the waveforms are always active and are only enabled when a physical switch is thrown. If this is so, it's likely you are getting leakage from the frequency generators. You may be able to counter this by adjusting down the gain on the initial phase, but this may result in the loss of functionality...
Otherwise, some shielding around the generators may reduce it.
What is your power source, batteries or a power supply? Maybe tie down the ground better.

- My multimeter has various modes for measuring resistance, which one should I use for testing resistors, looking for short circuits etc? Sometimes its doing nothing at all, even when I touch the probes together (should show zero resistance, right?) Am I doing something wrong or could there be a fault with the multimeter?

Yes, when in resistance mode (ohms symbol) touch the probes together should give close to 0, or less than 1 ohm. If the meter has a continuity buzzer, turn this on a see if it works. If not, lump it back to Maplin!

- The soldering went reasonably well, however as the night progressed the iron started "spitting" bits of smoky solder although I tried to keep it clean and tinned. Do I need to get some sort of solder cleaner/flux? I was under the impression that solder has a flux core, maybe not in my case. Should I get eye protection in case a gob of solder finds its way in there? Any other tips for cleaning/preparing my components, PCB and soldering iron tip?

Spitting may be a sign of too much flux in the solder or too high a temperature. As you can't control either of these you can only choose a lighter grade (thinner) solder next time!
Don't worry too much about it. Just keep the smoke away from your nose/mouth and eyes.