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Hero999
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Posts posted by Hero999
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You hyjacked this thread instead of starting your own thread.
I was going to split the thread but his post is on topic so it doesn't matter.
im building a musical doorbell that needs a 2sc828 transistor. can i replace it using any other transistors?
You may get more help if you post the schematic. -
I think he is probably right, a pen is too small. If there was a way it'd be only be able to be used once after each charge.
There are other things to consider such as, in order to kill, the electricity ideally needs to pass through the heart and a pen is too small for the electrode spacing to be wide enough.
A more effective solution would be to fill the pen with poison and inject it.
As you want help from a professional, how much are you willing to pay? -
I think it's a spammer. I deleted the post but undeleted it as it's vaguely on topic.
I doubt it'll give you a better link. -
The only dumb thing about this question is not enough information is given to answer it. Whether a capacitive discharge is fatal or not depends on many factors, including the person being shocked. A tiny static shock may be enough to trigger a heart attack in very vulnerable person yet many people report surviving shocks from much lager capacitances charged to high voltages.
In scientific papers statistics such as the 50% lethal dose are given but in this case it still depends on many factors. The voltage and capacitance are obviously important but there are others such as skin moisture and where the electrodes are placed. -
Because the components and PCB tracks are only rated to pass a maximum current of 400mA. If you try to draw any more, there's a risk it could overheat or some protection circuitry will kick in (the latter is more likely) and reduce the output voltage, therefore the current (Ohm's law).
To increase the current capacity you'd need to replace some of the components with ones with higher current ratings (this isn't possible without an understanding of how the circuit works) and widen some of the tracks on the PCB which would require a redesign of the PCB.
Oh and by the way, in future when starting a thread, please use a more descriptive title than just help. Consider what you need help with. There are many help threads here and there's more chance people will read it if the title gets their attention. -
The short answer is no, you need to buy a power supply with a higher current capability.
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You forgot to attach the photos.
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Thanks for posting your project.
I think the best solution for the inductor is winding your own. A ferrite core designed for use in an SMPS would be ideal. -
All right, you're not trying to do what I thought which was measuring its own power supply.
The first thing which could be wrong is the 7660 isn't needed, as you already have a negative supply, so it needs removing.
Secondly, what's the transformer's voltage rating? The filter capacitor values appear to be too small.
And Finally, have you made all the 0V connections? -
Where's the schematic? Please stop asking questions without one.
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How are we supposed to help without a schematic?
I did a quick Google for the typical configuration for the said IC and assuming you're using the standard set-up I don't know why you're surprised, you're short circuiting the power supply. -
Yes, why not?
The only thin you need to beware of is the minimum operating voltage will now be 6V, rather than 2V but it will definitely last for longer. -
Sorry, no ones going to do your project for you. This is not a free electronic design service, I apologise if that's not clear. Electronics Lab is a forum where people help each other with their projects.
If you want someone to design your project for you, they'll more than likely charge you a fee and require you to supply them with a design specification first. -
Where's the schematic and code?
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A twisted pair will do but for optimum noise immunity, you need a screened cable.
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The chemical used to develop PCBs is NaOH. It doesn't need to be a strong solution, 0.6% will do.
The substance used to coat the board before exposure to UV is known as a photresist. Many different chemicals are used, each having different properties, see Wikipedia for more information.
http://en.wikipedia.org/wiki/Photoresist
Using the sun to expose PCBs isn't very reliable. It's much better to use a popper light box which is easy to make yourself.
Here's another site with more information on DIY PCBs.
I mostly use the toner transfer process myself and when I do use the photo process I buy pre-sensitised copper clad board. -
It sounds reasonable to me considering what you've measured is the off-load voltage before all of the losses in the rectifier and driver transistors.
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Is 81VAC the voltage you've measured of the transformer?
115V into 8R will give a theoretical maximum output power of 827WRMS. You've calculated the peak power which is double.
In reality, the actual power output will be much lower as there will be losses in the rectifier, driver transistors and the voltage across the capacitors will sag under load due to them being discharged and their ESR. If the maximum output voltage is 99V, under full load conditions, the RMS output power into will be 600W. In reality the maximum output voltage will probably be even less than 99V so I doubt it'll really deliver the full 600W.
You're right about the capacitors being underrated, I'd suggest replacing them with 160V or higher, with has low ESR and as higher temperature rating you can get and them not being too large to fit on the board. -
All right, I'll respond.
Where's the code and a detailed write-up of the project?
Your soldering is horrible, especially the two LEDs dangling off the end of the board.
I notice you're using Q1's base current to drive another LED, is that to save power?
What does D1 do?
Finally why are you here? You seem to be more interested in publicising your site than anything else. I've not pressed the delete button because your projects are interesting and on topic but just you let you know, you're on my list of potential spammers. -
i want to know where and why ttl logic is used
It isn't used, not any more, far newer technologies have succeeded TTL which was very power hungry and exhibited poor performance. -
How can he provide such an in-depth answer without the schematic? That's impressive. ::)
What sort of LC oscillator are you talking about?
There are many configurations. The only thing you hint at, is you're using a BJT.
Here are some examples:
http://www.sentex.ca/~mec1995/tutorial/xtor/xtor7/xtor7.html
In all circuits, the base is connected to the LC tank in some way, perhaps that should give you a clue.
If you want a decent answer, post the schematic. -
LTSpice is one of the most popular simulators in hobbyist circles. It's a powerful SPICE simulator and you can easilly creat your own models from the datasheets.
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None of your links work.
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http://www.batteryjunction.com/tlunlichfor1.html
How to amplify a square wave cheaply at 100 Hz?
in Electronic Projects Design/Ideas
Posted
Kevin,
A voltage multiplier converts AC to DC so isn't an option and the rest of your post doesn't make any sense.
plukins,
An audio amplifier may oscillate, as it won't be designed to drive a capacitive load.
Are you looking to build this yourself or buy off the shelf?