Hero999

Yes you did miss the mark by not providing enough information: schematic, PCB layout, pictures etc. - we're electronic engineers not mind readers.

LTSpice will run on Linux under WINE. There are also many open source alternatives available, try searching the Ubuntu software repository.

How are we supposed to know?

I mean a 20 to 50 Ohm potentiometer. It really isn't critical, there doesn't need to be any impedance matching. The potentiometer just needs to have a low enough resistance to avoid being loaded too much by the headphones but high enough not to overload the sound card. If the resistance is too high, the volume will be too low when the potentiometer is in the middle setting, when the output resistance is half its value. If the resistance is too low, it will draw too higher current from the sound card output.

Tolerance is normally specified as +/-20% or more typically -20/+80% for such a capacitor. If it has a tolerance of 10% then that's too good to be true for an aluminium electrolytic capacitor.

Yes, it's a standard aluminium capacitor.

I recall having a similar problem with some threads. Have you sent mixos and email or private message?

Firstly, measure the resistance between both gates (connect them together) and drain and source, the resistance should be near infinite, >100M. Secondly connect both of the gates to the drain. Measure the resistance between the drain (meter positive) and the source meter negative), it should be under 1k. Finally connect the 5V supply's positive to the source and negative to the gates. Measure the source - drain resistance, it should be much higher than the previous measurement >1M.

It's a depletion MOSFET. It's normally on (low resistance between the drain and source) when the gate voltage is zero. When the voltage on the gates is negative with respect to the source, there will be a high resistance between the drain and source. The resistance between the gates and drain/source should always be infinite. You can test it using the meter's resistance setting and bias the gate with a 6V battery or a small power supply, 5V will do. http://www.angelfire.com/electronic2/index1/40673.pdf

It's not too critical. Just use 20R to 50R and it should be fine.

Using a higher Ah cell shouldn't cause a problem as long as the fuel gauge can be properly recalibrated. I think the whole article is a bad idea though. I doubt you'll save any money rebuilding a battery pack. If you're drawn to cheap cells available on ebay then think again; they're probably old and Lion batteries do age even if they're not used.

Then use 15000uF or 10000uF with 2200uF in parallel.

You might get more help if you post in English and not posting the same thing more than once. The latter is against the rules. Making duplicate posts is treating as spamming and repeat offences will result in a ban.

How much cooking do you do? A microwave and toaster are all you need most of the time. Just make sure you get a decent brand not no-name Chinese trash.

I don't see why it wouldn't work. The ILC7660 would need a voltage regulator to reduce the supply voltage to below 10V. Look at the datasheet of the ILC7660 for its maximum output current rating. Calculate the negative supply current taken by U3 when the output voltage is 0V. If it's above the ILC7660's maximum rating it won't work. You could use the 555 timer and some diodes as an alternative which would work as long as the current through the 555's pin 3 is below 200mA.

What's the output current? Have you considered an off the shelf solution? A power supply designed to run of universal mains input will probably do. The Puls ML50.100 (datasheet linked below) may suit you; it will work from 85VDC all the way up to 375VDC, the output voltage can be adjusted to 28V and is galvanically isolated from the input which makes it safer than a buck converter. http://www.pulspower.com/pdf/ml50e101.pdf Why reinvent the wheel?

My guess is they're something like 100nF but I can't be sure. This project is typical for this website: incomplete and may not even work. The use of opto-couplers where no isolation is required is bizarre and the circuit appears to be drawn an an almost deliberately confusing manner.

I think a programmable IC is a good idea, PIC and AVR microcontrollers and programming hardware can be bought fairly cheaply nowadays. Why not go for LEDs rather than a cold cathode tube? They're no nast high voltages to worry about and no mercury or glass.

How long to you want it to last for? You don't have large enough batteries to light that many LEDs for more than a couple of minutes at best.

Seams fairly simple to me. Connect the LEDs in strings of as many as the power supply voltage will allow, each with its own series resistor and use a power MOSFET to switch each bank of LEDs.

Here's a simple push-pull transistor amplifier. It has a power output of just 250mW. With a few modifications and a higher voltage power supply, the power can be increased to 5W with a much lower quiescent current and lower distortion than a class A amplifier with a transformer. http://www.silicontronics.com/index.php?action=ezportal;sa=page;p=21

It's always better to use a capacitor with a higher voltage rating than the intended power supply voltage. 16V is the minimum voltage rating for a capacitor connected to a 12V system.

A DC motor doesn't need a regulated power supply. Buy a 6V transformer with the desired current rating, connect it to a bridge rectifier and run the motor from that. If you need a smooth DC power supply to run a microcontroller you can use a voltage doubler circuit and the LM7805 to dereive a separate, smooth 5V supply.

Buy a 5V mains adaptor such as the sort used to power a mobile phone, cut off the plug and solder the wires to the battery terminals.

The answer is to use an audio amplifier IC such as the LM386, TDA2822, TDA7052, TDA7053 etc. The schematic is on the datasheet which can be found using a search engine.