[QUOTE=Cakebatyr;46531623]
That is, assuming you're running on an Arduino Uno.[/QUOTE]
no, it's a digispark, i mentioned it briefly in the original post but you can also see it connected in the top right corner of my breadboard. it's USB only
[editline]20th November 2014[/editline]
it's also a half height usb port, which I enjoy the look of haha
I took a 9V battery got low enough to not work in another dude's project, he was using a 7805.
My thing is using an LM2596, I've sucked the battery down to 5.85V, it's hilarious.
µC is still working fine, but the LEDs are getting dim, and the output voltage from the LM2596 so isn't even close to the 3.3V I set it to.
Also, my lots of LM2596 from Aliexpress arrived.
10 days from China to me, with free shipping. Bloody hell that was fast.
[QUOTE=nikomo;46540531]I took a 9V battery got low enough to not work in another dude's project, he was using a 7805.
My thing is using an LM2596, I've sucked the battery down to 5.85V, it's hilarious.
µC is still working fine, but the LEDs are getting dim, and the output voltage from the LM2596 so isn't even close to the 3.3V I set it to.
Also, my lots of LM2596 from Aliexpress arrived.
10 days from China to me, with free shipping. Bloody hell that was fast.[/QUOTE]
You're using a 9V Battery to power a 3.3V regulator? Ouch...
[QUOTE=DrDevil;46541070]You're using a 9V Battery to power a 3.3V regulator? Ouch...[/QUOTE]
A quick search says the LM2596 is a switching regulator?
Ouch in terms of power dissipation or noise?
I knew these things were pretty small but [I]damn[/I].
[t]http://i.imgur.com/f4CuMPM.jpg[/t]
Yep. Perfect for integration with an ATtiny.
If you have the version with the LED near the antenna there is a firmware update out that allows you to set the baud rate of the chip to 9600
I'm waiting on three more of them to arrive, I may have killed the first two I got with 5V. I'll build a voltage divider this time... Though I should really invest in some 3v Arduino Mini Pro clones.
[QUOTE=papkee;46545827]I knew these things were pretty small but [I]damn[/I].
[t]http://i.imgur.com/f4CuMPM.jpg[/t][/QUOTE]
whats this?
nfr24l01 communication module most likely.
[editline]22nd November 2014[/editline]
great for sending data to and from other devices at close range, i.e. sensors in corners of your room.
[QUOTE=DrDevil;46541070]You're using a 9V Battery to power a 3.3V regulator? Ouch...[/QUOTE]
It's a switching step-down converter, it's pretty efficient.
[editline]22nd November 2014[/editline]
Also, here's my thing right now.
I have it counting through from 0 to 9 and just looping that right now, to test that everything works properly electrically.
[t]http://i.imgur.com/AIgGBSJ.jpg[/t]
On Monday, I need to figure out how the hell the 1Wire protocol thing works, the temperature sensor uses it.
[QUOTE=benjgvps;46546311]I'm waiting on three more of them to arrive, I may have killed the first two I got with 5V. I'll build a voltage divider this time... Though I should really invest in some 3v Arduino Mini Pro clones.[/QUOTE]
You are talking about using a voltage divider for the logic lines, right? You can't power an active component with a voltage divider.
[QUOTE=scratch (nl);46547293]nfr24l01 communication module most likely.
[editline]22nd November 2014[/editline]
great for sending data to and from other devices at close range, i.e. sensors in corners of your room.[/QUOTE]
Pretty sure it's an ESP8266.
[QUOTE=alexaz;46548237]You are talking about using a voltage divider for the logic lines, right? You can't power an active component with a voltage divider.[/QUOTE]
Right, the arduino I'll be using has a 3.3v regulator that will power it, though the serial port is 5v.
[QUOTE=scratch (nl);46547293]nfr24l01 communication module most likely.
[editline]22nd November 2014[/editline]
great for sending data to and from other devices at close range, i.e. sensors in corners of your room.[/QUOTE]
ESP8266 TTL UART controlled WiFi module.
[QUOTE=Fourier;46547266]whats this?[/QUOTE]
It's an ESP8266 wifi module. It's like $5 on ebay and is great for anything you would need to be internet connected.
That is cheap as fuck.
I ordered some on Aliexpress when they had the sale, $2.77 a piece with free shipping. I ordered three.
Also, they released an SDK for the microcontroller that's handling it all, so if you're doing something simple, you can just straight-up use the ESP8266 board, by itself.
Additionally, I found some DIP CPLD's in an old video mixer I was tearing apart. Anybody on here use PLDs? They seem very interesting and I'd love to get in to doing something with them.
[QUOTE=alexaz;46548237]You are talking about using a voltage divider for the logic lines, right? You can't power an active component with a voltage divider.[/QUOTE]
You can, the resistors just have to be low enough value to prevent the output voltage dropping under load, if the current draw is rather low like <1mA it can work rather well.
1mA at 3.3V is an equivalent resistance of 3.3k, in order to prevent excessive loading of the divider the divider resistors must be chosen so the parallel combination (of the divider resistors) is no more than 330 ohms (10x impedance rule), a good choice would be 390 and 820 ohms, this has a parallel resistance of 264.3 ohms, so now the thévenin equivalent circuit is 3.3V in series with 264.3 ohms, in to a 3.3k load this gives a voltage drop of 0.245V which is only 7.4% low, good enough in most cases.
[editline]22nd November 2014[/editline]
Forgot to mention that the total current is 4.78mA which means you're pissing away 3.78mA on just the voltage divider, so it might be okay in some circuits like mains powered, proper voltage regulators are cheap as dirt anyway these days.
Sounds like a decent way to cut down on production costs, though, if you just need to provide a milliamp or so to something.
You could also use a zener diode to build a crude regulator.
Aren't zener diodes expensive though?
Not really, although one major downside of zener voltage regulators (I.E the 78**) is they have a fairly high quiescent current drain usually on the order of 5mA to 30mA which can be a issue in low power applications, the load regulation of zener diodes is also pretty poor by themselves, most good regulators use a bandgap voltage reference instead, although that has its own downsides.
[QUOTE=Chryseus;46552194]Not really, although one major downside of zener voltage regulators (I.E the 78**) is they have a fairly high quiescent current drain usually on the order of 5mA to 30mA which can be a issue in low power applications, the load regulation of zener diodes is also pretty poor by themselves, most good regulators use a bandgap voltage reference instead, although that has its own downsides.[/QUOTE]
I'm not talking about the 78xx series, I'm talking about this:
[img]http://www.electronics-tutorials.ws/diode/diode24.gif[/img]
Do you guys see any problems in having 3 sets of 4 18650's in series producing a nominal 14.4V,
and isolating the sets by p channel mosfets into a capacitor so that they don't try and put current into each other and does not matter if they are of unequal charge capacity (my charger can only take 4 batteries, so it would be nice to be able to have a set on charge and 2 sets in the device).
Regulating the charge in the battery sets using pwm via a microcontroller?
You will have to make sure the cells are balanced, just like a 3 cell LiPo battery.
[QUOTE=DrDevil;46552554]I'm not talking about the 78xx series, I'm talking about this:
[img]http://www.electronics-tutorials.ws/diode/diode24.gif[/img][/QUOTE]
Same thing applies, the zener diode has a minimum current requirement in order to remain in the reverse breakdown region which is around 5mA at lower voltages, also that is pretty much the worse regulator circuit only suitable for low current drain, unless you use a very small resistor so the zener gets a high amount of current, within power dissipation limits of course.
Something like this is more useful:
[img]http://u.cubeupload.com/Chryseus/M9TacI.png[/img]
Due to the voltage drop of the transistor base-emitter junction you need to pick a diode with a breakdown voltage 0.6V higher than your intended output voltage, or 1.2V if you use a darlington pass transistor.
[QUOTE=Chryseus;46555173]Same thing applies, the zener diode has a minimum current requirement in order to remain in the reverse breakdown region which is around 5mA at lower voltages, also that is pretty much the worse regulator circuit only suitable for low current drain, unless you use a very small resistor so the zener gets a high amount of current, within power dissipation limits of course.
Something like this is more useful:
[IMG]http://u.cubeupload.com/Chryseus/M9TacI.png[/IMG]
Due to the voltage drop of the transistor base-emitter junction you need to pick a diode with a breakdown voltage 0.6V higher than your intended output voltage, or 1.2V if you use a darlington pass transistor.[/QUOTE]
As an aside, this circuit is the reason why "weird" Zener voltages e.g. 12.6V, 5.6V are so commonly available.
Bluetooth remote sensor! I think this is the smallest PCB design/hand soldering I've done yet (The small black spec below/left the Atmega is a boost converter that supposed to boost up from a 3V coin cell to 3.3V). It passed the smoke test so now its time to program it via the ISP header I stuck on it.
[img_thumb]http://oi59.tinypic.com/xlgoiw.jpg[/img_thumb]
[img_thumb]http://oi58.tinypic.com/2mowhg4.jpg[/img_thumb]
Sorry, you need to Log In to post a reply to this thread.
