Reconn's World Forum

mic amplifier

guest — Sat, 08 May 2010 12:51:12 -0700

It's simple. A speakerphone telephone when using the speakerphone (telephone mic) the person at the other end always says, "you sound like your speaking into a tunnel," or something like that. It's not the same as speaking into the handset. Is there a way (schematic) I can amplify the speaker mic to make transmission louder?

Phil

Re: Car Battery to AC inverter

guest — Tue, 09 Mar 2010 00:21:11 -0800

Does anyone know how can i get 220VAC with wopping 300W rating from a 12VDC battery B)-

Re: 4 Channel Color Organ

guest — Tue, 01 Dec 2009 19:25:32 -0800

Hello

Nice circuit & just what I have been looking for!

Looks like there is an E1 on the lower right corner...looks like a place a mic input (?)

Re: 12 volt battery monitor

guest — Tue, 13 Oct 2009 10:15:40 -0700

Pls,i want 2 know d circuit diagram for 12volt battery monitor

Re: 555 timer 40khz IR Oscillator

guest — Wed, 26 Aug 2009 20:37:18 -0700

hey...

i just wondering why?? the signal wave at output pin 3 is not a square pulse..instead, i got a straight line with some voltage value...
is it sometin to do with the 555 timer??is it damaged??or might be due to any other reasons???...

plz help...help..sigh..hehe

Re: ultrasonic switch

guest — Sun, 11 Jan 2009 01:21:44 -0800

Hello,

in the circuit's description you write:

Quote

5. Ultrasonic waves are emitted by many natural sources. Therefore, sometimes, the circuit might get falsely triggered, espically when a flip-flop is used with the circuit, and there is no remedy for that.

However, there is a remedy for that, albeit it would require a few additional parts.

First, use a second 555 (or any other oscillating circuit) at a very low frequency of only a some hertz. Let that control the transmitter's 555, so that it will output a pulse train instead of a continuous signal.

Then, use a counter chip, like a CD4017 in the receiver. Instead of feeding the relay driver transistors, feed the counter's clock input. Select an output of the counter to drive the relay driver. Also, add a NPN transistor or N_channel FET between the clock input and GND, connect it's base (or gate) to the selected counter output. This is to make the counter stop once the selected step is reached, despite further incoming pulses.

Finally, add an RC circuit between the op-amp's output and the reset input of the counter so that it resets after a while when no more pulses are incoming. For this to work properly, the impulse on/off ratio needs to be "uneven", that is, not 1:1 (see below).

Doing this, sporadic ultrasonic impulses don't make the relay trigger, as long as the pause between them is bigger than the RC constant on the reset line. If you select, lets say, the 9th output of the 4017, it will switch only after 9 pulses that must come in fast enough.

That's just an rough overview of the addition. Some things depend on the used counter, like the on/off time ratio. Also, depending on the counter, an additional transistor may be needed to inverse the signal, depending on the counter needing a low or a high signal for the reset.

Hope that idea is useful,

Chris

Re: Zapco PS200 DC/DC Converter

guest — Mon, 08 Dec 2008 16:02:53 -0800

I have one of these power moduals. I picked it up at a car boot sale.
The 12 vault in put doesnt seem to be putting out anything, Do you know anything about it?

Mike

Pressure Switch info

guest — Sun, 07 Dec 2008 16:55:03 -0800

Hello,

(Please reply to: phillipv at nb.sympatico.ca)

I need to identify some sort of pressure sensor(s) with which to be placed at specific anatomical read-points along the Exo-frame:

1. Inner wrist for biceps contraction
2. Outer wrist for triceps contraction
3. Mid-biceps for shoulder raise
4. Just above elbow for rear shoulder raise
5. Upper knee for hip raise
6. Rear lower-leg for hip swing back

Need to be able to set a threshold for the sensors for each position�s EoCL (Edge of comfort level). If the threshold is not triggered, the joint remains un-actuated and under the pilot�s power. Or perhaps some variant of this method that proportionately increases the actuator power with the amount of force registered by the sensor. This selective passivity will allow for a greater amount of power conservation and employ more natural stored energy release for things like the Contra-Postal walk that kind of feeds itself energy via the spinal torsions, arm swing and hip swing.

Phillip

Please reply to: phillipv at nb.sympatico.ca

Re: 5 volt power supply

guest — Sat, 06 Sep 2008 18:21:09 -0700

Hey,

I found this site from googling 5v power supplies, I was going to order the parts and didn't find a 4A Bridge rectifier. I went back to check the schematic and in the picture it has a 1A ontop the bridge rectifier. Could someone that build it already or knows off hand, tell me weather i should get a 1amp bridge rectifier instead?

Thanks
~Z
Life_Drained[at]hotmail[dot]com

HELP ME PLSSSS.......

guest — Tue, 19 Aug 2008 05:46:44 -0700

can you kindly help me...

can you give me a schematic diagram for a transistor based power supply AC to DC

output voltage:

2.5
5.5
8
10
12

thx...i need di as soon as possible...

email me at thugsterz_15@yahoo.com

HELP ME PLSSSS......

guest — Tue, 19 Aug 2008 05:43:59 -0700

can you kindly help me...

can you give me a schematic diagram for a transistor based power supply AC to DC

output voltage:

2.5
5.5
8
10
12

thx...i need dis as soon as possible...

email me at thugsterz_15@yahoo.com

HELP ME PLSSSS......

guest — Tue, 19 Aug 2008 05:43:49 -0700

HELP ME PLSSSS.......

guest — Tue, 19 Aug 2008 05:40:43 -0700

TRANSISTOR BASED POWER SUPPLY AC to DC

guest — Tue, 19 Aug 2008 05:39:06 -0700

TRANSISTOR BASED POWER SUPPLY AC to DC

guest — Tue, 19 Aug 2008 05:38:19 -0700

can you kindly help me...

can you give me a schematic diagram for a transistor based power supply AC to DC

output voltage:

2.5
5.5
8
10
12

thx...i need di as soon as possible...

High frequency ring tone detector

guest — Thu, 17 Jul 2008 13:03:12 -0700

I was wondering if anyone had a diagram to build such a device. I need something to ID when such tones are ringing in a classroom.

Re: Stun Gun

guest — Thu, 24 Apr 2008 15:28:48 -0700

If you are looking for full blown diagrams on making a stun gun, you can find them on our site located @ [StingerDefense.com]

We do sell both Stun Guns and Taser, however I do have several diagrams on how to build them located at the link above.

Thanks,
Nate Neel - VP
Stinger Defense
Stun Guns, Pepper Spray, MACE and Tasers
[www.StingerDefense.com]

Re: Stun Gun

guest — Wed, 23 Apr 2008 02:13:23 -0700

guest Wrote:
-------------------------------------------------------
> Here is a Stun Gun Schematic.

Of course, a stungun these days only costs around 20 bucks. And I figure that would be a whole lot better built and reliable...

Have a look here [www.StingerDefense.com]

Re: 555 timer 40khz IR Oscillator

Justin9 — Fri, 22 Feb 2008 20:28:24 -0800

I would like to use this for a project I'm working except I will be using 12 volts instead of 5volts and I have have 8 infrared leds... can someone help me get all the resistors right?

andrew Wrote:
-------------------------------------------------------
> [www.reconnsworld.com]
> 40khzir.jpg
>
> parts:
> U1 555 Timer IC
> R1 47 ohm resistor
> R2 470 ohm resistor
> R3 5k variable resistor
> C1 0.0047uf ceramic capacitor
> LED1,LED2 Infrared LED's
>
>
> This circuit oscillates two infrared LED's at 40
> khz. To make sure it is transmitting IR light, you
> can get a little tool from radio shack for about
> $5. It is a small sheet of plastic about 1" by 3"
> with a special strip of material, that when
> exposed to IR light glows (it's actually kinda
> cool..) A way to check for 40khz IR light is to
> build a circuit that lights an led when 40khz
> light is detected. You can get the schematic by
> clicking here.

A circuit to generate between 16 khz and 20 Khz Ultrasound

pedro — Tue, 22 Jan 2008 15:15:55 -0800

Hi Everyone!

I'm new at this f�rum. I'm not good at electronics, but I like to make some gadgets at home.

I'm trying to find, in the WEB, some circuits to produce 16 Khz Ultrasound. I'm planning to make a gadget with it.

I, only, found a circuit to produce 40 to 50 Khz Ultrasound, but I think it is very high for my project.

Can anyone help to find it?

Thanks. Sorry about my english. It isn't very good.

Pedro

what amps RMS

mercy — Thu, 25 Oct 2007 18:36:01 -0700

I am another one of those guys that dont know anything but am trying to find out relevant things. Whan looking at a schemaic, how can you determine what the RMS watts of an amp is?
Thanks

Re: Solar Charger

jimboy123 — Thu, 23 Aug 2007 19:40:11 -0700

can i see the diagram?

Re: basic ir detector/emitter

felix — Wed, 18 Jul 2007 09:48:09 -0700

Hi, I want to data log the IR pulse on my domestic electricity meter.

Can I use the detector side of of the above circuit posted by andrew to sense the pulse or is there a better circuit for this application?

The pulse signal will be counted by a Dallas 1-Wire counter.

Many thanks for your help.

Re: basic ir detector/emitter

felix — Wed, 18 Jul 2007 09:36:31 -0700

andrew Wrote:
-------------------------------------------------------
> [www.reconnsworld.com]
> etectemit.gif
>
> parts:
> R1 270 ohm resistor
> R2 10k resistor
> LED1 Infrared LED
> Q1 Infrared-sensitive photoresistor
>
>
> This is a very basic infrared detector/emitter
> circuit. One major downside of this circuit, is
> that ambient infrared light will interfere with
> its detecting obstacles.

Simple Tube Amp

ag1722 — Sat, 31 Mar 2007 21:42:28 -0700

Hi,
I'm looking for a schematic for a simple tube amp that would run on DC/batteries... I was hoping to use some tubes I already have such as a couple of 1S4's . Can anyone help?

Bill
ag2217@yahoo.com

Re: 12 volt battery monitor

Bob D — Tue, 13 Mar 2007 10:50:36 -0700

I built this circuit, and the LED stays on until the voltage drops below the trip point. I thought that the LED would light when the voltage dropped below the set point ? Am I missing something or did I construct the circuit wrong ?

8 Watt amp problems

grandpaslincoln — Sun, 18 Feb 2007 16:37:59 -0800

I built the 8 watt amp from schematics I found here [www.aaroncake.net]

However, I could not locate an LM383 or an ECG1232 that the parts list showed as an alternate amp IC. I read somewhere on the net (can't remember where) that an NTE7143 20W IC can be used in place of the others. I built the amp, but can't get it to work. It comes on, but all I get out of the speaker is a hum. The IC gets pretty hot as well even with a heatsink. I shut it down because I'm afraid of burning up the IC. Did I use the wrong IC? What other IC's can I use in place of the others? I added the 0.02 uF cap and a 2 Ohm resistor in the circuit per what the the website listed above. Anyone got any ideas?

12V power supply for amp

grandpaslincoln — Sun, 18 Feb 2007 16:30:45 -0800

I'm building a guitar amp and need a clean 12V power source. I bought a 12V transformer at Radioshack, and am wondering what kind of circuit I can build to clean the power up so it doesn't hum. I've been searching the net for a couple of weeks but have yet to find what I'm looking for. If anyone can help, it would be greatly appreciated.

Thanks,
Jon

Re: voltage doubler

rfrary — Fri, 05 Jan 2007 00:19:25 -0800

I'm a little late with my reply, so I guess this is for anyone else that may be considering a similar portable power pack.

The thing that needs to be considered here is 'energy' or 'power output over time'.

"The oem charger outputs 12v's via firewire 6pin adapter
orginally, I was thinking about using 8 aa's (1.5v) in series to get
12v's... but this is incredibly bulky... so i was hoping for a way to get
12v's with less batterys. This circuit will allow me to do so with 4
batterys right?"

First let me say that I know nothing about ipods power requirements. So I will use your supplied info with a worst case scenerio, that is; 12 volts @ 1 amp.

A typical alkaline AA battery is rated at 2700 mah, or 2.7 amp hours. That doesn't mean that it will produce 2.7 amps for an hour, What it does mean is that it SHOULD produce 270 ma for a period of 10 hours. That's way short of your required 1 amp.
A typical alkaline 'D' cell battery is rated at 18000 mah, or 18 amp hours. Ok so here we have a battery that has the capacity to supply the needed 1 amp. Now string 8 of them in series and you will have a portable charger that will last approx 18+ hours at 1 amp load. But this really doesn't fit your desire to make it small. Nevertheless for a moment let's say that you would be content with a size of 4 'D' cells = 6 volts -> voltage doubler circuit -> 12 volts into ipod. Problem solved right? Wrong! You can't get energy for free.

12 volts at 1 amp = 12 watts. This is what your battery pack will be required to produce (assuming for simplicity that you used a perfect, 100% efficient, lossless voltage doubler), regardless of the number of cells or their voltage.

Therefore, using 4 'D' cells, you have 6 volts from which you must draw 12 watts. Ohms law tells us that 2 amps will be required, which once again puts the power draw over the battery's rating. Though the batteries can supply 2 amperes, their useful life decreases severely with the increased current.

The bottom line is that there is no way that 4 AA's will do what you want. Your best bet is to make a car cigarette lighter adapter to charge your ipod, unless of course you are a hiker or mountain climber (or have a phobia of cars), in which case it would not be practical to carry your car along with you.

Hope this helps somebody.

:smile:

Re: ultrasonic switch

chintan_bme — Tue, 10 Oct 2006 06:35:09 -0700

can i use this circuit for an ultrasonic range meter? how??