I need to make a fan controller.

[shadow]

Originally Posted by Mad_Professor

Wow that's crazy.

Anyways,
I'm ordering my stuff from digikey.

But I don't know what kind of inductor I want?

I'm guessing the one I want is going to be "FIXED" but there are so many variables and types, Half the stuff in the columns doesn't make any sense to me.

Also does AREF need a ceramic cap?

I just checked the datasheet for the ATMega168 microcontroller. It is a bit confusing, however it says that analog reference voltage can be set to either AVCC, 1.1V or an external voltage connected to the AREF pin. For your case, I would suggest that AVCC is the most appropriate setting (and probably the default configuration). The datasheet does also say that you can connect AREF to ground using a small capacitor (the ceramic capacitor you are talking about) for greater noise immunity.

Therefore I would say it is up to you whether you place a capacitor there or not. I do not think it will greatly affect the operation of the circuit for your purposes.

[Agent24]

Just get a low-current axial inductor\choke. They look like a 1/2 watt resistor but a little larger. Yes it will be fixed value.

If you can specifiy on the website you want an axial one, and then input the value (100uH I think it was?) and then sort by price, you should find the cheapest one will probably be suitable.

(Like this: http://jaycar.co.nz/productView.asp?...H&form=KEYWORD)

I don't really know the function of AREF. I don't think it needs a capacitor, but I am not sure. The Arduino I built did not have one on it.

[shadow]

Originally Posted by Agent24

I don't really know the function of AREF. I don't think it needs a capacitor, but I am not sure. The Arduino I built did not have one on it.

The datasheet did say it is optional, however adding it would achieve greater noise immunity to the ADC. So it is not needed but it is nice to have. I did check the schematic for the official Arduino and they did include it (not like that means that much ).

[Agent24]

Originally Posted by shadow

The datasheet did say it is optional, however adding it would achieve greater noise immunity to the ADC. So it is not needed but it is nice to have. I did check the schematic for the official Arduino and they did include it (not like that means that much ).

The Uno and others might have it, but the Severino I built doesn't. (Basic plain serial, no USB, on a single-sided board)

[Mad_Professor]

SO I put together a part's list, I just want someone or everyone to double check and correct me on any items.

I plan on building two of these, one for the application and one for fun. You know to mess around with. It could be used for a backup should I screw up..

Controller:

2x Atmega168 chips
*not sure if it's the correct chip since there were multiple ones to select from.
http://search.digikey.com/scripts/Dk...44424527095246

6x kemet 0.1uf 50v Ceramic caps
http://search.digikey.com/scripts/Dk...44424527095246

2x 10k Ohm Resistors
http://search.digikey.com/scripts/Dk...44470209430126

2x 10UH Inductor choke
http://search.digikey.com/scripts/Dk...44470209430126

5x TIP120 Darlington Transistors
http://search.digikey.com/scripts/Dk...44470209430126

5x 1N5817 Schottky Diodes
http://search.digikey.com/scripts/Dk...44470209430126

5x 1k ohm resistors
http://search.digikey.com/scripts/Dk...44470209430126

1x 10k ohm linear rotary potentiometer
*not sure if this is what I need.
http://search.digikey.com/scripts/Dk...44501353013998

2x 4pin 8981 Molex connector
http://search.digikey.com/scripts/Dk...44474047585041

2x 6pin header
*making a inline ICSP interface for my DAPA cable.*
http://search.digikey.com/scripts/Dk...44474047585041

1x 28 pin IC dip socket
*hope this is the correct one. I don't want to destroy the chip with my iron or should the chip become fubar, easy replacement.
http://search.digikey.com/scripts/Dk...44474047585041

5x 3pin headers with friction lock
http://search.digikey.com/scripts/Dk...44474047585041


NOTE:
I already have the low frequency decoupling caps which is panny 47uF 50v FC series cap.
Also I don't have a prototyping board, I'll decide on that when I get a chance to play with Veecad and veroDes this weekend.


DAPA cable *parallel programmer:
1x 220 ohm resistor
http://search.digikey.com/scripts/Dk...44474047585041

2x 470 ohm resistors
http://search.digikey.com/scripts/Dk...44474047585041

I already have the Parallel cable, actually, I have a box full of them to hack up.

I'll put the order in sunday, if everything looks good

[mariushm]

The links aren't working...

These seem to be the ones you're looking for:

http://search.digikey.com/us/en/prod...-PU-ND/2271215
http://search.digikey.com/us/en/prod...10PU-ND/735447
http://search.digikey.com/us/en/prod...20PU-ND/735446

There may be slightly cheaper ones running at 10Mhz or lower, but I don't really think it's worth the trouble... these run at 20 Mhz and they should be perfect for your needs.

Other than the last being more power sensitive (2.7v-5.5v vs 1.8v-5.5v for the first two) I don't see any differences. They all go in 28-DIP (0.300", 7.62mm) so you need to get a 28-DIP with 0.300" spacing:

So I guess these should work:

http://search.digikey.com/us/en/prod...0210-ND/990628
http://search.digikey.com/us/en/prod...480-ND/1133633

Basically search for "DIP socket", then filter by one category at a time, 0.300" 7.62mm , then through hole/wire wrap , and so on...

Make sure your computer actually has a parallel port, some USB to parallel adapters don't work for flashing these devices.

ps. Since you're gonna power this from 5v most likely, you may have spikes of power on 5v that are over 5.5v comin from the power supply... most power supplies also do by default about 5.1-5.3v ... the chips will probably resist some spikes of power but it wouldn't hurt getting something like this:

http://search.digikey.com/us/en/prod...CTFS-ND/458700

This takes 7-35v and delivers 5v @ 500mA (minimum), which should be enough to drive the controller.

[Mad_Professor]

Originally Posted by mariushm

The links aren't working...

These seem to be the ones you're looking for:

http://search.digikey.com/us/en/prod...-PU-ND/2271215
http://search.digikey.com/us/en/prod...10PU-ND/735447
http://search.digikey.com/us/en/prod...20PU-ND/735446

There may be slightly cheaper ones running at 10Mhz or lower, but I don't really think it's worth the trouble... these run at 20 Mhz and they should be perfect for your needs.

Other than the last being more power sensitive (2.7v-5.5v vs 1.8v-5.5v for the first two) I don't see any differences. They all go in 28-DIP (0.300", 7.62mm) so you need to get a 28-DIP with 0.300" spacing:

So I guess these should work:

http://search.digikey.com/us/en/prod...0210-ND/990628
http://search.digikey.com/us/en/prod...480-ND/1133633

Basically search for "DIP socket", then filter by one category at a time, 0.300" 7.62mm , then through hole/wire wrap , and so on...

Make sure your computer actually has a parallel port, some USB to parallel adapters don't work for flashing these devices.

ps. Since you're gonna power this from 5v most likely, you may have spikes of power on 5v that are over 5.5v comin from the power supply... most power supplies also do by default about 5.1-5.3v ... the chips will probably resist some spikes of power but it wouldn't hurt getting something like this:

http://search.digikey.com/us/en/prod...CTFS-ND/458700

This takes 7-35v and delivers 5v @ 500mA (minimum), which should be enough to drive the controller.

Thanks for telling me the links were dead.

I have the last avr you listed in my basket already. do you think I should go to the one of the others?

Also my desktop computer does not have a parallel port but I do have some old computers and old main boards I can easily load up with XP or Linux.

As for the voltage regulator..
I have a corsair TX 750 PSU in the server, do you really think it might spike?
You know what, I don't want to play with fire so I'll add them in with two panny 47uF 50v FC caps.

So Let me try this again...

Controller:

2x Atmega168 chips
*not sure if it's the correct chip since there were multiple ones to select from.
http://search.digikey.com/us/en/prod...20PU-ND/735446

6x kemet 0.1uf 50v Ceramic caps
http://search.digikey.com/us/en/prod...4264-ND/818040

2x 10k Ohm Resistors
http://search.digikey.com/us/en/prod...0CT-ND/1830374

2x 10UH Inductor choke
http://search.digikey.com/us/en/prod...135-ND/1305993

5x TIP120 Darlington Transistors
http://search.digikey.com/us/en/prod...120-ND/1052441

5x 1N5817 Schottky Diodes
http://search.digikey.com/us/en/prod...SCT-ND/1532776

5x 1k ohm resistors
http://search.digikey.com/us/en/prod...0CT-ND/1830487

1x 10k ohm linear rotary potentiometer
*not sure if this is what I need.
http://search.digikey.com/us/en/prod...308-ND/2408885

2x 4pin 8981 Molex connector
http://search.digikey.com/us/en/prod...6988-ND/951582

2x 6pin header
*making a inline ICSP interface for my DAPA cable.*
http://search.digikey.com/us/en/prod...1963-ND/109069

1x 28 pin IC dip socket
*hope this is the correct one. I don't want to destroy the chip with my iron or should the chip become fubar, easy replacement.
http://search.digikey.com/us/en/prod...286-ND/1628669

5x 3pin headers with friction lock
http://search.digikey.com/us/en/prod...112-ND/1130578

ADDED:
3x panny FC 47uF 50v
http://search.digikey.com/us/en/prod...0321-ND/266330
*I have an extra one at home to make 4.

2x 78M05 voltage regulators
http://search.digikey.com/us/en/prod...CTFS-ND/458700

NOTE:
Also I don't have a prototyping board, I'll decide on that when I get a chance to play with Veecad and veroDes this weekend.


DAPA cable *parallel programmer:
1x 220 ohm resistor
http://search.digikey.com/us/en/prod...RCT-ND/1830334

2x 470 ohm resistors
http://search.digikey.com/us/en/prod...RCT-ND/1830342

I already have the Parallel cable, actually, I have a box full of them to hack up.

I'll put the order in sunday, if everything looks good

[mariushm]

Not sure about those inductors, Agent or someone more knowledgeable should give you feedback on that.

For the resistors, it depends on what you're going to use them for... for some uses the 5% tolerance may be too much ... that makes the 10k resistor anything between 9500 and 10500 ohm.. 1% resistors shouldn't be that hard to find and they're not that more expensive.

If it's just to light a led, 5% resistors will be fine, but if you want to use them for PWM or determine a ratio using the potentiometer and a resistor, I would probably go for 1% tolerance.

I don't know if 10k for potentiometer is enough, not sure how you're using it. If it's gonna be for the controller to detect a voltage between 0 and 5v on a pin and convert that to digital with the ADC, maybe a larger resistance value would give you a wider variation...

2x 6pin header *making a inline ICSP interface for my DAPA cable.* ...check the pitch and make sure it will match with your existing connector.... this one you selected has pitch 0.156" (3.96mm)

If you plan to make the cable from scratch just go at the bottom of the page for that one and select from "mating products" a "mother" connector (the connector you plug those pins into), for example one of these (digikey is a pain, lists 500 mating items, most are non stock or minimum 2000 to order):

http://search.digikey.com/us/en/prod...1647-ND/769791
http://search.digikey.com/us/en/prod...1244-ND/696766

You just pull out the metal connectors inside with the help of a needle and then press the wire and plug back the connector in the plastic case.

As for the power supply... it's a good one, but won't provide you with 5v sharp, it will most likely give you a bit more than that on the cables, 5.3 or something like that.. the atmega will probably tolerate more than the max of 5.5v but why risk it when the prevention is less than a dollar?

[Agent24]

The inductor looks fine to me.

Originally Posted by mariushm

I don't know if 10k for potentiometer is enough, not sure how you're using it. If it's gonna be for the controller to detect a voltage between 0 and 5v on a pin and convert that to digital with the ADC, maybe a larger resistance value would give you a wider variation...

Well, the 555-based fan controller that I posted earlier uses a 10k pot and it works great, so I guess it would be OK here too. Then again, it goes between 12v with a 9k resistor on each side, so, yeah.....


With the 0.1uF Capacitors and the 10K Resistors, you might as well buy several more. I usually purchase about 30+ of each when I order something like this, so I have more for next time I want to do something.

Those values especially are very commonly used too, so it makes sense to have a few spare, and they are cheap.


Not sure why you're using a 78M05. It can only supply 500mA while a normal 7805 can supply 1 Amp. Though for this usage I doubt it will make any difference though. Again, you might want to buy several for future use, in which case, the higher current ones might be better.


Everything else looks fine, but I don't see a crystal, if you are using one.

Speaking of crystals, a good thing to note is the dielectric type of the ceramic capacitors, which affects stability due to temperature variations etc.

There are several different types. The ones you picked are X7R which are good for non-critical purposes but for crystal loading capacitors and other things where you want better stability it's better to use C0G/NP0 types.

http://en.wikipedia.org/wiki/EIA_Class_1_dielectric
http://en.wikipedia.org/wiki/EIA_Class_2_dielectric

[Scenic]

Originally Posted by Agent24

Not sure why you're using a 78M05. It can only supply 500mA while a normal 7805 can supply 1 Amp. Though for this usage I doubt it will make any difference though. Again, you might want to buy several for future use, in which case, the higher current ones might be better.

A ST-made 7805CV can supply up to 1.5A .. in case he buys a bunch of those for other projects, that might come in handy. Kinda funny how that one can deliver 3 times the current yet it costs 1 cent less..
http://search.digikey.com/us/en/prod...43-5-ND/585964

[Agent24]

But don't forget that if you do want to get that much current out of it you need a big heatsink...

[lti]

A 78L05 might work fine. Does that microcontroller draw more than 100mA? I have an ATMEGA48 microcontroller that worked fine from a 78L05.

[shadow]

Originally Posted by lti

A 78L05 might work fine. Does that microcontroller draw more than 100mA? I have an ATMEGA48 microcontroller that worked fine from a 78L05.

I checked the datasheet for the ATMega48/88/168 microcontroller and it does say the ABSOLUTE maximum current that it will draw is 200mA. The current draw is a function of the operating frequency, the operating voltage, the amount of devices connected to the microcontroller etc.

However in nearly all configurations I believe the current draw would be within 100mA.

In fact the datasheet really advertises how little power it consumes, in particular if you reduce the operating frequency and use the built in oscillator. For example, the ATMega48/88/168 draws 250uA at 1MHz and a supply voltage of 1.8V. Another example is that it draws 15uA at 32kHz and a supply voltage of 1.8V while making use of the internal oscillator. Pretty amazing stuff in my opinion.

[shadow]

Originally Posted by Scenic

A ST-made 7805CV can supply up to 1.5A .. in case he buys a bunch of those for other projects, that might come in handy. Kinda funny how that one can deliver 3 times the current yet it costs 1 cent less..
http://search.digikey.com/us/en/prod...43-5-ND/585964

I encountered this sort of thing a lot while designing my own circuits. Buying components which fit the purpose more (closer to the actual maximum ratings and usually smaller form factors) in fact cost more than the 'more commonly' used components. So I ended up severely over-specifying some of my circuits to keep costs down.

This is particularly true with the switching transistors I used to design my fan controller. I designed it using a Darlington transistor that can output up to 5A, however I could use a Darlington transistor in a smaller package that would be more appropriately rated for the job at hand if I pay 2-3x more.

[Agent24]

But that smaller transistor may have been 3x faster hence 3x the price.

In any case, in my opinion, over-engineering something is never a bad thing!

[Mad_Professor]

Ok so I'm working in tinycad since veecad needs a netlist to place components.

Anyways I just realized something, do I need to have digital outputs for each set *1k>tip120>fan* that say PWM on the arduino pin out or can I use one PWM output to control the 5 transistors?
If I can't then can I use any pin that says digital I/O?

http://arduino.cc/it/Hacking/PinMapping168

This left side of the chip and place the chip to the right on the board.
I was going to use,
digital I/O PWM pin 3/actual: pin 5 on chip
digital I/O PWM pin 4/actual: pin 6 on chip
digital I/O PWM pin 5/actual: pin 11 on chip
digital I/O PWM pin 6/actual: pin 12 on chip

I want to use
Digital I/O pin 7/actual: pin 13 on chip
But it doesn't say PWM. I don't know if I can use it as PWM connection.

I was going to put the pot on the right side of the board too and connect it to where it says analog PC0.

Then below the chip put my DAPA header and run the lines to the right side of the chip.
Then the left side can be used for tip120, diodes and resistors and headers.

[Agent24]

Originally Posted by Mad_Professor

Ok so I'm working in tinycad since veecad needs a netlist to place components.

I would advise getting into the habit of drawing up a schematic and getting a netlist, it might take extra time but it's worth it, because then you can't make mistakes on your board layout.

The software will only let you connect in the board layout what is already connected in the schematic and netlist.

(Of course, this works the other way too, if you make a mistake in your schematic, that flows through into the netlist and board layout)


I'll let someone else answer your other question about the PWM pins, I'd probably get it wrong!

[Mad_Professor]

Originally Posted by Agent24

I would advise getting into the habit of drawing up a schematic and getting a netlist, it might take extra time but it's worth it, because then you can't make mistakes on your board layout.

The software will only let you connect in the board layout what is already connected in the schematic and netlist.

(Of course, this works the other way too, if you make a mistake in your schematic, that flows through into the netlist and board layout)


I'll let someone else answer your other question about the PWM pins, I'd probably get it wrong!

Veecad is just fucking useless. I made my schematic. I export it using protel format and when I import it into Veecad it comes out as U shape components. Then when I try to add TinyCad libraries to Veecad and try to import again, it says ERROR: File version information not found. If I remove all the tinycad Libraries from veecad then it works but all U shape components are back.

I'm too tired and I can't get Veecad to work, so fuck it.

I went ahead and change my resistors from 5% to 1%.

What changed:
78M05 replaced with this
MC7805CT-BPMS-ND

Replaced 220 ohm resistor with this
PPC220YCT-ND

Replaced 470 ohm resistor with this
RNF14FTD470RCT-ND

Replaced 1k ohm resistor with this
RNF14FTD1K00CT-ND

Replaced 10k ohm resistor with this
RNF14FTD10K0CT-ND

ADDED
A31647-ND *Locking Ramp MTA-156 connector*


This is what my layout looks like in tinycad. Now I got to figure out what size stripboard, actually I might buy it locally.

[Agent24]

Originally Posted by Mad_Professor

Veecad is just fucking useless. I made my schematic. I export it using protel format and when I import it into Veecad it comes out as U shape components.

This might be a stupid question, but why are you exporting to Protel format?

[Mad_Professor]

Because I don't see a veecad on export or a tinycad on import option.