Showing posts with label indicator. Show all posts
Showing posts with label indicator. Show all posts
Friday, October 31, 2014
Isolated Fuse Fail Indicator Circuit Diagram
This is the simple Isolated Fuse Fail Indicator Circuit Diagram. This circuit uses standard components and shows a method of indicating the fuse status of mains powered equipment while providing electrical isolation from the mains supply.
Isolated Fuse Fail Indicator Circuit diagram:
Isolated Fuse Fail Indicator Circuit Diagram
A standard miniature low power mains transformer (e.g. with an output of around 6 V at 1.5 VA) is used as a ‘sense’ trans-former with its primary winding (230 V) connected across the equipment’s input fuse so that when the fuse blows, mains voltage is applied to the transformer and a 6 V ac output volt-age appears at the secondary winding. The 1N4148 diode rectifies this voltage and the LED lights to indicate that the fuse has failed. The rectified voltage is now connected to an RC low-pass filter formed by the 10 kΩ resistor and 100 nF capacitor. The resulting positive signal can now be used as an input to an A/D converter or as a digital input to a microcontroller (make sure that the signal level is within the microcontroller input voltage level specification). The 1 MΩ resistor is used to discharge the capacitor if the input impedance of the connected equipment is very high.
As long as the fuse remains intact it will short out the primary winding of the ‘sense’ transformer so that its secondary out-put is zero.
Saturday, October 25, 2014
3 Level Audio Power Indicator Circuits Diagram
This circuit is designed to indicate the power level output of any audio amplifier. Its simple, portable, and displays three power levels can be adjusted to any desired value.
3 Level Audio Power Indicator Circuits Diagram
Parts:
R1__________100K 1/4W ResistorR2___________50K 1/2W Trimmer Cermet
R3__________330K 1/4W ResistorR4____________1M2 1/4W ResistorR5__________470K 1/4W ResistorR6,R7_______500K 1/2W Trimmers Cermet
R8____________1K5 1/4W ResistorR9-R11______470R 1/4W ResistorsC1___________47pF 63V Ceramic CapacitorC2__________100nF 63V Polyester CapacitorC3___________47µF 25V Electrolytic CapacitorC4____________1µF 25V Electrolytic CapacitorD1______BZX79C5V1 5.1V 500mW Zener DiodeD2_________1N4148 75V 150mA DiodeD3-D5________3mm. Yellow LEDs
IC1_________LM339 Quad Voltage Comparator ICSW1__________SPST Slider SwitchB1_____________9V PP3Clip for 9V PP3 Battery
Circuit operation:
This circuit is intended to indicate the power output level of any audio amplifier. It is simple, portable, and displays three power levels that can be set to any desired value. For a standard HiFi stereo power amplifier like the 25W Audio Amplifier described in these pages, the power output values suggested are as follows:- D5 illuminates at 2W
- D4 illuminates at 12.5W
- D3 illuminates at 24.5W
IC1A is the input buffer, feeding 3 voltage comparators and LEDsdrivers by means of a variable dc voltage obtained by R5 and C4 smoothing action. In order to achieve setting stability, the supply of IC1 and trimmers R6 & R7 is reduced and clamped to 5.1V by Zener diode D1.
Notes:
- The simplest way to connect this circuit to the amplifier output is to use a twisted pair cable terminated with two insulated crocodile clips.
- Setup is best accomplished with an oscilloscope or an audio millivoltmeter like the one described in these pages. Precision Audio Millivoltmeter
- A 1KHz sine wave generator with variable output is also required (see a suitable circuit in this website also). 1KHz Sinewave Generator
- Connect the generator to the amplifiers input and the Audio Power Indicator to the output of the amplifier, in parallel with the oscilloscope probe or the audio millivoltmeter input.
- When using high power outputs disconnect the loudspeakers to avoid Tweeters damage and connect in their place an 8 Ohm 20-30 Watt wirewound resistor.
- Remember that VRMS output is equal to output Peak-to-Peak Voltage divided by 2.828.
- RMS power output in Watts is equal to VRMS2 divided by speaker impedance (usually 8 or 4 Ohm).
- Example: set the output of the 1KHz sinewave generator to read 14V on the audio millivoltmeter (24.5W @ 8 Ohm). Set R2 until D3 illuminates, and be sure that D3 turns-off when diminishing a little the generators output.
- Do the same with R7 for D4 and R6 for D5. The readings of the audio millivoltmeter must be 10V (12.5W @ 8 Ohm) and 4V (2W @ 8 Ohm) respectively.
Saturday, August 23, 2014
Stereo balance indicator
You can use this schema to modify your own amplifier.this shows the out put sound level.you can use this one for various things.
Notes.
* The schema can be assembled on a Vero board.
* Use 9V DC for powering the schema.
* Mount IC1 on a holder.
* C1 ,C2 and C3 must be rated at least 6V.
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