Hero999

With the values shown the calculated frequency range is 85MHz to 225MHz. In practise it'll be lower, more like 80MHz to 160MHz.

I wouldn't recommend a PC 'scope unless it's a really advanced one. PC 'scopes tend to lack features found in a simple analogue 'scope: they normally only have one channel and no external trigger input. Someone else bought this Chinese 'scope and they like it, order code: 85-2792. I've never used it though. http://www.rapidonline.com/Tools-Fasteners-Production-Equipment/Test-Equipment/Oscilloscopes/PDS-Series-2-channel-colour-oscilloscopes/80709

That circuit has, no RF buffer amplifier, so the frequency will drift if objects are placed near the antenna, no voltage regulator, so the frequency will change as the battery runs down and no pre-emphasis so it will sound like an AM radio. I'd recommend using this circuit which has all of the above and the inductor values are clearly marked. http://www.silicontronics.com/index.php?action=ezportal;sa=page;p=15

Please translate this into English; sorry I don't understand gibberish.

Then buy a driver and bingo, you have a totally finished circuit. Yes, the datasheet says it's isolated so there will be a transformer. However, it's an SMPS so it'll have a small ferrite cored high frequency transformer, not a laminated iron 50/60H power line frequency transformer. Buy it, open it up, look at the ICs used, get the datasheets and reverse engineer the PCB.

The are lots of threads that dealing with the 30V power supply and yes you're right some are missing. The thread linked on that page is missing. I also made some bugfix threads for various projects here (including the 30V power supply) which have all gone missing. This is looking a bit like Stalinist Russa: mysterious disappearances. The site has had problems with the server recently and I have also had problems with other moderators deleting threads they shouldn't, probably mistakenly. I've had a quick look through the bin and can't find anything. I'll have another more thourgh look and will contact the administrator. There's not much I can do about this, I'm only moderate a couple of sections.

That will work, it certainly has the advantages of being cheap and simple. However it's not regulated and is inefficient as the resistor will wate lots of power.

What topic? there are hundreds of topics here. I know the site went down a few days ago, it must have been lost then.

I know, I wasn't suggesting you should should use a wall wart on its own, that would be a silly idea. The idea was to use a wall wart in conjunction with the Buck puck driver I suggested previously. The driver you've suggested looks perfect for powering an LED off the mains, no need for a wall wart.

mir_as82, As I'm sure you've been told before, use a wall brick power supply.

I think I can see where you went wrong: it's the 74HC14. They don't, it's a totally different circuit which has nothing to do with the 555. You can use either the 555 or the 74HC14s. As you need 12, using two 74HC14s will work out cheaper than six 556s but it's up to you, it depends on what parts you have available. Oh, I missed that, my circuit will blink on-off 50%-50% duty cycle. You want on 95%, off 5% don't you? Then the schematics will need a coule of modifications.

As I've said above, it's on the datasheet, as you appear to have forgotten how to use Google, here it is. http://tamarisco.datsi.fi.upm.es/ASIGNATURAS/FMI/COMPONENTES/MM74HC14_(InvSchmitt).pdf You only need to change the value of R2, for 4.5V and two LEDs in series use 150R. Heck way not use a flashing LED? Just connect it in series with a non-flashing LEd and a suitable series resisto and off you go. Each flaching LED will have a slightly different flash rate so they'll be slighlty out of phase and will all end up turning on and off at totally different times.

By the way the R2 in the previous schematic should have been 47R, with 330R it 3V it would be too dim. I thought you wanted a fader? A blinker is much simpler. The pinout for the 74HC14 is on the datasheet which can be found using Google. If you want two LEDs then use a >6V power supply and put tw LEDs in series. For 6V and two LEDs R2 should be 120R. Note that the maximum supply voltage for the 74HC14 is 6V.

350mA is quite a lot of current for an LED. Here's a driver that will do what you want. http://www.leddynamics.com/LuxDrive/datasheets/3021-BuckPuck.pdf

Was that my circuit you built? The frequency should have been about 0.5Hz if assembled correctly. Are you sure you've not used a 220nF capacitor or soldered it in the wrong way round? The frequency is roughly equal to the following formula: F = 1.1/(C1

You're not listening - there's a huge difference between a MOSFET and a BJT.

Here's the simplist way of doing it.

I replied before but it got lost,so here it is again. You can boostrap the power supply of the micro controller. Note that the duty cycle can never reach 100% because some off time is required to charge C1. You don't need a PIC, a 7555 will do. The schematic has calculations for working out the capacitor vale and maximum duty cycle.

Yes, lots of commercial power supplies are now switched mode, although one does occasionally bump into the odd linear power supply; most commonly in audio PSUs and AC adaptors.

An alternative to building a transformer is to simply put a tap in the middle of the inductor, the apparent impedance of the load will be increased by a factor of four and the voltage across it will be halved so the power will be down by a factor of four.

MOSFETs can be cheaply purchased with on resistances as low as 5mΩ so the voltage drop is only 50mV at 10A. I wouldn't say that 5V is a high voltage unless you want to power the device from two AA cells. Using a MOSFET invariably saves power, especially in DC applications. To achieve a good saturation voltage with a BJT ther base current typically needs to be 1/10th of the collector current and if the circuit driving the base is the same voltage as the collector load, 10% of the power is wasted on driving the transistor. Using a MOSFET in an application such as this will result in a 9% power saving. BJTs are better at higher voltages. A MOSFET's channel resistance increases exponentially with increasing break down voltage while the saturation voltage of a BJT remains roughly constant. At some point (around 400V) the on voltage loss becomes lower with BJTs compared to MOSFETs and if the base drive circuit is powered from a lower voltage than the collector circuit, then the power wasted driving the transistor drops. IGBTs are now replacing BJTs now in high voltage switched mode power supplyies so the BJT is becomming less common all the time.

MOSFETs have a faster switching speed, lower on loss and are easier to drive than BJTs, the gate also requires no current, at DC.

TV remote only emit IR when they're activated. A solution to the problem already exists: fit the remote with a passive transponder (similar to those used as an anti shoplifting device) which can be found using a suitable detector.

Yes, the output impedance will be equal to the impedance of the inductor and capacitor in parallel. The impedance of an ideal inductor and capacitor in parallel is infinite, in reality is won't be infinite but it'll be very high and depend on the Q of the tank. Any load connected to the output will reduce the amplitude and stability of the oscillator because it will affect the Q of the resonant circuit.

What did you use to power the transmitter? Was it a cheap unregulated wall wart or a battery or regulated wall wart/mains supply? I've tried powering an FM transmitter from a chap wall wart and it made the radio hum rather than transmit sound from the mic. You need to power it from a steady DC source such as a battery or regulated mains supply.