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Hero999
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You can use the LM78L05 if you like but the battery won't last as long.
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I told you about the problems with that circuit before.
You haven't even answered my question.
I give up, you're on your own, as you don't seem to want to help yourself, I don't see why I should help you. -
I discovered this a couple of days ago, sorry for not reporting it to the administrator.
Use a image hosting site such as www.tinypic.com -
Which components can't you get hold of?
It's possible to substitute some of the components.
Rapidshare has limited downloads per day unless you pay, for images use www.tinypic.com which has limitless sownloads. -
mey alum nignog si.
un pigo sog fin workin 4 u pwp up proply wiv u so pwr led. -
500m through what? Free space, a forest or town?
What receiver are you using? A cheap Chinese FM radio won't be able to pick it up from as far away as well as a state of the art car radio.
What aerial are you useing? A high gain yagi array will transmit/receive the signal from a long away but will be more directional, a simple monopole will not transmit/recieve the very var but will pickup/send the signal in all directions. -
I've already done that, read my first reply to this thread.
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A piece of copper clad some etchant like Ferric Chloride, a Tupperware bowl and a sharpie pen. All for around 20 bucks or less. With a little practice and a few add ons your boards are only limited by your imagination.
Whilst the sharpie pen will work, I wouldn't recommend it because it's very time consuming and doesn't give very good quality boards.
I would recommend toner transfer. Print the artwork using a laser printer, iron it to the board using an ordinary clothes iron, soak in water and remove the paper, leaving behind the toner which is stuck to the board, and etch in the usual manner.
Many people swear by special propriety papers, normal printer paper will work and clay coated magazine paper is best, in my opinion.
Note that, you need to use a laser printer, don't even bother with inkjet because it won't work. If you don't have a laser printer then you could get it photocopied at the local library. -
Who's RED?
Yes, use a magnetic speaker.
I'd be tempted to get rid of R6 and use a 64Ω speaker or magnetic sounder. -
The "piezo sounder" is not a beeper, it is a transducer (speaker) that is driven at about 2.7kHz by the oscillator made from IC1C and driver transistor Q1.
I see, it's a Schmitt trigger oscillator.
The trouble is, it isnt' the correct way to drive a piezo which is a capacitive load. You ideally need a push-pull driver, otherwise it will be very quiet indeed.
As drawn, there is nothing to discharge the capacitive piezo transistor so it won't do much; moving R6 in parallel with the piezo will increase the volume by providing a discharge path.
Alternatively, get rid of Q1, R5 and R6 and connect the piezo directly to the output - it'll make the circuit simpler and louder. -
Sorry, I can only answer questions 2 and 4 because the others are very poorly worded and don't make any sense.
2.why pin"14" of IC2 is grounded by C4?
C4 is a supply bypass capacitor, it reduces the impedance of the supply to higher frequency. Digital circuits tend to draw brief high current surges which will cause the supply voltage to momentarily drop; the capacitor acts like a little battery by supplying current during the surges, helping to keep the supply voltage up. Without the capacitor there is a risk that the circuit could become unstable due to fluctuations in the supply voltage.
There should ideally be a 100nF capacitor across the supply pins of each IC but you might be able to get away with using one electrolytic capacitor.
4.function of Q1 in circuit
Q1 turns on the piezo buzzer when pin 10n on IC1 goes low. -
Sorry I can't help you, I've just had to Google MPPT.
It sounds like a very interesting project though. -
22E is the alternative reference of 22 ohms.
Lots of circuits refer to values such as 2E2 = 2.2 ohms, 680E = 680 ohms,
1E5 = 1.5 ohms, 330E = 330 ohms and so on .
I am sure this arises from the missing "omega" (ohm) font in most computers.
I don't know where you heard that but it seems wrong to me, perhaps it's foreign? It certainly isn't English.
Normally the letter R is used if it isn't possible to use Ω, for example: 22R = 22Ω, 2R2 = 2.2Ω and 0R22 = 0.22Ω. For larger values the prefix can be used instead of the decimal place, 2k2 = 2.2kΩ = 2,200Ω.
I've seen the letter W used on some foreign articles but never the letter E.
In my view the letter E should never for Ohms be used because it can be too easily be confused with the exponent, for example 125E3 = 125 -
Start your own thread.
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A lead acid battery will charge very slowly if charged to 13.8V.
If it's charged to 14.5V and reduced to 13.8V when the current drops below a certain level, it will charge much quicker. -
A simple first order low pass filter will do that.
Above twice the cut-off frequency, the roll-off will be 6dB/octave. -
Why did you ask for a circuit that works, if you were only going to build a different one that doesn't work?
I could be many things.
Are you powering it from a mains adaptor? The internal capacitor might not be large enough so add a 1000 -
I should can this response.
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. -
http://www.silicontronics.com/index.php?action=ezportal;sa=page;p=15
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Posting the schematic would help.
Generally 100nF ceramic capacitors are used for decoupling but sometimes 2.2 -
So its on YouTube so it must be true. ::)
How about posting a link?
It's probably fake. -
The meter will have an impedance of 10M so to divide by 10, all you need to do is connect a 90M high voltage resistor in series with it. This can be made using nine 10M resistors in series, each resistor needs to be rated to 1/10th of voltage being measured.
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A super-hetrodyne receiver.
You can buy one for a fraction of the cost of making one. -
If you just want to one PCB, then it will cost a lot more per unit than if you wanted a large quantity.
If the PCB is fairly simple, i.e. no solder resist or through hole plating and just single/double sided, you can make it yourself which is much cheaper than having it custom made for you.
I've always made my own PCBs for home projects, I got some made at at work, but I just handed the Gerber files and drawings to the purchasing department, who found a supplier and did the rest.
re tv antenna amplifier fm/uhf/vhf
in Projects Q/A
Posted
What preamplifier are you talking about?
Please post a schematic?