[DrLuke]

Make sure to put a heatsink with a fan on it on the hot side.

[XeNo]

I'm joining this competition in which we have to make an automatic line following robot(as has been done loadsa times)

Everything should work great but we don't know what motors we should get.
The robot won't weigh more than 1kg(probably a lot less) and it should be able to go atleast 1m/s

We don't really know how much torque and rpm it needs though so if anyone could help us, that'd be great

We need 2 motors and were thinking of geared dc motors http://be02.rs-online.com/web/c/auto...t-option=Prijs

But we don't want to waste money on motors which are too powerful so could someone give us an example of a motor which would suit our needs, thanks

[LoneWolf_Recon]

This helped me alot:
http://www.societyofrobots.com/RMF_calculator.shtml

[OrYgin]

Finally got around buying an arduino. Hoping sparkfun delivers quickly.

[Tw34k]

OrYgin posted:

Finally got around buying an arduino. Hoping sparkfun delivers quickly.

Yeah, they ship pretty quickly. Shoulda bought just the AT328 and built your own arduino :P

[OrYgin]

Tw34k posted:

Yeah, they ship pretty quickly. Shoulda bought just the AT328 and built your own arduino :P

I don't think I could've done this :p

However, I'm not in the US, so maybe it'll slow down.

[Tw34k]

Honestly all a arduino is, is just a breakout board with a power regulator and usb-serial interface. The last of witch isn't always even needed.

[Zero-Point]

Tw34k posted:

Honestly all a arduino is, is just a breakout board with a power regulator and usb-serial interface. The last of witch isn't always even needed.

Arduino is more of an improvement on the development side, kinda like a DirectX for microcontrollers (more specifically ATMega chips).

[VistaPOWA]

Tw34k posted:

Yeah, they ship pretty quickly. Shoulda bought just the AT328 and built your own arduino :P

You do that when you want to finalize a design. Programming an AT328 takes you an AVR programmer to burn in the Arduino code, an Arduino as ISP then you can only re-program it using an Arduino.

[DrLuke]

I personally believe that the arduino is a great stepping stone for beginners of electrical engineering. It allows you to very easily get started with some simple projects without setting up too much hard- or software. Even further down the line it can be used as a good prototyping platform, but eventually everybody who wants more will grow away from the arduino and move on to AVRs.

For artists who just need a simple tool that works, the arduino is perfect and exactly what they need. They don't want any hassle to get their art done, they just want it to work.
Just imagine if you wanted to get into sculpting, but you first have to make the hammer and chisel yourself, which would turn off the most of us.

Anyways, my point being: If you really want to advance further into electronics, you'll eventually have to ditch arduino and get your hands dirty with AVRs. The change will be very hard, because all of the sudden you have to do everything arduino did for you before, but you get to see what actually happens and you can even make things operate differently (The ADC or using Pins is a good example for that).

I only use the arduino for really really quick prototyping and as a power supply due to it's convenient power-barrel-jack with the broken Vin pin, that allows me to access a wallwart without having to fiddle around with the barrel-jack.

[SubbyV-2]

Zero-Point posted:

110VAC. I've got a 3A peltier wafer lying around and I'd like to make a tiny fridge out of it.

Would an atx power supply not suffice?

Ddrl, you always have something against atx power supplies, explain the problem with them in an intelligent form please?

[DrLuke]

When I powered my peltier, I found out it was to be powered at exactly 15V and would draw 6A. So I bought a 15V 7A Laptop charger and used that to power the peltier! I got ice forming on it, but I probably would've achieved better results with a bigger heatsink and fan.

[SubbyV-2]

Oh god double post, 110vac to 12vdc at 4a inst easy

Might order myself a peltier to play with, what kind of wattage can a old amd cpu cooler put up with?

[MIPS]

I ahd a friend who glued a peltier tot he bottom of his coffee mug to act as a warmer.
It didn't work because the mug insulated it and when he tried tot ake it off he split it in two.

[SubbyV-2]

Got my tube! now just gotta work out a 250Vdc boost converter, 6.3v regulator, 12v to -10v, and non inverting amplifier

[DrLuke]

MIPS posted:

I ahd a friend who glued a peltier tot he bottom of his coffee mug to act as a warmer.
It didn't work because the mug insulated it and when he tried tot ake it off he split it in two.

Yes, peltiers without a heatsink self destruct within seconds.

[Zero-Point]

SubbyV-2 posted:

Would an atx power supply not suffice?

Ddrl, you always have something against atx power supplies, explain the problem with them in an intelligent form please?

Nah, I want this fridge to be just big enough to put a water bottle in it. Would like it to be a complete unit but I guess I could settle for a brick PSU. :/
I've powered it with an ATX supply before, was pretty fun. Even put it on the CPU in my mineral oil PC. Kept it cool... At idle. I knew it wouldn't do much at load, I was just curious is all.

[MIPS]

The rest of my day was spent learning about what has been done with the Mattel Juice Box since I last owned one in 2005.



Seven years later, here I am with one and in that time the systems have been totally documented and NOTHING HAS BEEN FUCKING DONE WITH IT.
I don't get it. Here you have something that can play fair bitrate audio and display low resolution pictures and video and so far the most hardcore hacks done with it was to modify the loaded linux distro and make an XD memory adapter. Nobody even messed with how to package your own videos.
I'm tempted to mess with it but it seems that everything you can do with it has already been done so is there really much of a point?

[SubbyV-2]

Anyone know how to get a clock out of a crystal?

[DrLuke]

SubbyV-2 posted:

Anyone know how to get a clock out of a crystal?

http://www.z80.info/uexosc.htm

[SubbyV-2]

DrLuke posted:

http://www.z80.info/uexosc.htm

thanks, but i realized i'll never get a 3KHz crystal.

[Aw_Hell]

SubbyV-2 posted:

thanks, but i realized i'll never get a 3KHz crystal.

You should try a real time clock IC, they range from small and simple:

http://search.digikey.com/us/en/prod...55ED-ND/805852

To big and fancy:

http://search.digikey.com/us/en/prod...55ED-ND/805852

[LoneWolf_Recon]

I've finished the power supply for the transmitter, and have completed roughly half of the main transmitter board. But I broke a pin on one of the variable caps so I'm outta luck right now :P

[ddrl46]

Aw_Hell posted:

You should try a real time clock IC, they range from small and simple:

http://search.digikey.com/us/en/prod...55ED-ND/805852

To big and fancy:

http://search.digikey.com/us/en/prod...55ED-ND/805852

He was talking about a clock signal not a time keeping chip.

[SubbyV-2]

Aw_Hell posted:

You should try a real time clock IC, they range from small and simple:

http://search.digikey.com/us/en/prod...55ED-ND/805852

To big and fancy:

http://search.digikey.com/us/en/prod...55ED-ND/805852

I didnt know these puts out clocks?

[Chryseus]

SubbyV-2 posted:

I didnt know these puts out clocks?

They don't.

Also MIT is doing a free online version of their analog electronics course.
https://6002x.mitx.mit.edu/
It starts March 5th.

[ddrl46]

You might remember this one from the first thread, replaced a 3 to 8 decoder and it works again:

[chipset]

ddrl46 posted:

You might remember this one from the first thread, replaced a 3 to 8 decoder and it works again:

I don't, what is it?

[ddrl46]

chipset posted:

I don't, what is it?

Intel 8085 system design kit.

[Chryseus]

Made a quick op-amp relaxation oscillator for Subby.



Slight modification, add 47uF from the virtual ground to the circuit ground, this cuts out quite a bit of noise.
There seems to be a step response on the rising and falling edge about 8us long, not exactly sure what is causing it.
Actually thinking about it, it could be the result of parasitic capacitance and inductance since it seems to get worse with increasing frequency.
Anyway it's not a problem unless you want a fast clean rise and fall, you could put it into another op-amp and use that as a simple comparator to get a clean output.

Changed the non-inverting feedback resistor to 100k, that seems to have greatly reduced any step but I'm still not completely sure as to how.

[DrLuke]

A fresh canvas

[Tobba.]

I was needing some high voltage for something, and I couldent find my brick sized HV transformer (how the fuck did I misplace this)

So as a quick and dirty soloution I ripped a flyback transformer out of an old CRT
Now to figure out the pinout of this

[Chezburger]

DrLuke posted:

A fresh canvas

Your puny canvasses are nothing compared to my sheets of uncut pcb

[LoneWolf_Recon]

Oh do you mean this?

[Chryseus]

Just finished shopping, bought:

100 UV LEDs
Tweezers set from dealextreme
Alcohol dispenser
Small flux container bottle
Solid rosin flux (for ultra cheap homebrew flux)
Samsung ML-1865 mono laser printer
Pack of ten 0.8mm drill bits
1L of isopropanol
500gr of sodium metasilicate pentahydrate
1kg of ferric chloride hexahydrate
two 100ml cans of positive spray photoresist
five single sided copper clad boards
20m roll of 90gsm tracing paper

All for £115, pretty good I think.
Time to get making them PCBs :-D

[DrLuke]

WIP

[LoneWolf_Recon]

What's on the blue board? Is that an Analog Devices' IC?

[ddrl46]

LoneWolf_Recon posted:

What's on the blue board? Is that an Analog Devices' IC?

DDS func gen.

[TVC]

Anyone know where I can get a good hobbyist Smartcard Reader/Writer, all I find a commercial ones which I'm afraid won't give me full access to the serial interface.

[DrLuke]

LoneWolf_Recon posted:

What's on the blue board? Is that an Analog Devices' IC?

It's a board for the AD9850, it can generate sinewaves from 0 to 125 MHz with a precision of 0.0291 Hz/lsb.

Edited:

TVC posted:

Anyone know where I can get a good hobbyist Smartcard Reader/Writer, all I find a commercial ones which I'm afraid won't give me full access to the serial interface.

Sparkfun carries one, but of course it's pretty expensive.