I have built one channel of the peak indicator below, but am having difficulty getting it to work as expected.
The output of the op amp sits at around 5V, and then drops to 1V when the upper threshold pot is adjusted with a signal applied (1KHz sine
4Vpp).I assumed the LED would light, but it does not; and I don't understand how it would in terms of the circui diagram.
I am probably missing something simple. Can someone please advise.
Mark Newman
The LEDs are backwards in the schematic.
The long lead is the cathode and should benegative when the lamp is on.
RL
I wish that circuit were a new low in published projects, but it isn't--bad as it is, there are lots worse. At least the op amp output moves, even if it can't actually light the LED.
For a start, no matter what the op amp does, the LED is reverse biased, so it will never light. This is because the op amp is powered from the
+12 rail, and it has no way to drag its output above the positive supply.For another thing, the circuit relies on the leakage of the diodes to bring the voltage on the noninverting input of the op amp back down from the peaks, and there's no hysteresis to keep it from oscillating.
Really a bad circuit. Have a look in Horowitz & Hill for better ones.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
"Phil Hobbs"
** Agreed.Even with the LEDs reversed, it ill still be almost useless.
The nature of audio signals is that the peaks are brief, too brief to visibly LED and of either polarity.
So, a proper design has a full wave rectifier stage, threshold detector plus a monostable acting as a pulse stretcher.
Ideally, peaks as short a 100uS that exceed the set threshold should make the LED flash for 100mS.
.... Phil
It looks to me as if the schematic has the LEDs wired up backwards.
The TLC272 op amp is being used as a comparator, as there is no feedback from the output to the inverting input. The noninverting input is being fed from a (fixed but adjustable) reference voltage.
The noninverting input is being fed from the signal source, through a diode which *tries* to keep the noninverting inpput from being pulled down below ground voltage (as this is outside the op amp's normal operating limits). I suspect that this protection is not terribly effective, since the noninverting input has an extremely high input impedance (I don't see any protective clamp diodes in the op amp equivalent schematic).
The way it's supposed to work: when the voltage on the circuit input is less than the (pot-adjusted) voltage at the "+" terminal, the op amp will be pulling its output "high", up to 12 volts (or as high as it can drive). Both terminals of the LED will be at about the same voltage and the LED will not light.
When the input value rises above the upper threshold you've set, and the "-" terminal of the op amp is higher in voltage than the "+" terminal, the op amp is going to pull its output down as low towards ground as it can (it's desperately "trying" to lower the inverting terminal voltage to match the noninverting terminal). This will pull one end of the LED down towards ground, through the 820R resistor, and cause the LED to light.
So, I see two problems with the circuit. The LEDs should be reversed (with the cathodes connected to the resistors, and the anodes connected to +12). And, I think you ought to place protective resistors (100k would probably suffice) between each op amp "-" input and ground, to give the 1N4148s something other than the op amp inputs to try to pull current through.
I do not know why you're only measuring +5 at the op amp outputs under "resting" conditions... it seems to me that the outputs should either be very near +12 or very near 0. By operating without protective resistors on the - inputs, you may have pulled the negative inputs down below the "absolute maximum rating" for the input voltage (which is -0.3 volts). This might have damaged the FETs in the input circuit and shorted something... in which case, replacing the op amp would be necessary.
Even with resistors, or a different arrangement of the 1N4148 protective diodes, you're still likely to end up pulling the - input down below -0.3 volts.
Frankly, from what I see, this circuit really needs a redesign.
tlc272/
As mentioned, it's a sucky circuit.
I suspect that some dufus scanned the circuit in from a magazine, in part because they didn't even bother to photoshop the ghost text from the back of the page out of the picture. Then they ignored whatever part number was actually called out and specified the '272
So:
Turn the LEDs around.
Put resistors between pin 2 and ground and 5 and ground of the '272. I'd start with 10k-ohm.
Give it a whirl. If you have an oscilloscope watch the voltage at the input to see if the mean value drops as current is pumped by D1 and D2. If so, then your amplifier is AC coupled. You can fix this by putting a resistor (1k-ohm?) to ground from each audio input pin.
Even without at O-scope you can measure the input voltage with a volt meter. It'll probably average out the audio and thus will probably show you the DC bias -- if it doesn't stay at 0V then you need the input resistor. If it doesn't _start_ at 0V, then you need the input resistor to ground, but you _also_ need a blocking cap (1uF would work down to about 250Hz or so, more is better).
Or, get yourself a copy of H&H and go from there.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
I agree with the others, it is not a good design. I also consider it useles s.
For one, if you want to detect clipping in an amp there are too many variab les for such a circuit with preset thresholds to do any dman good. It might tell you when a certain power level is exceeded but other than that it tel ls you nothing.
To detect clipping on an amplifier, you must detect a discrepancy between t he input ad output. First of all you need the right point for one of the in puts. That will be the input to the power amp stage after all volume and to ne controls and ANY other signal processing. Usually it is maybe 1 volt P-P for rated output.
The power amp circuit has a specific gain after this point and you have to null it. Here's a qwikndirty of it :
The box on the left is whatever, the preamp and everything like equalizers, dynamic range expanders and whatnot before the power amp. If you are deali ng with an integrated amp or a reciever without pre out/main in jacks you h ave to go inside and find the inputs to the power ampp itself. This is not difficult usually, except in newer junk where they try to force the space s huttle electronics into three square inches.
R1 and R2 simply take the level of the input side down to the point where i t is easy for the OP AMP to handle. On the output side, R3 and R4 match tha t level so that it nulls, that is to apply the same level to the + and - in puts of the OP AMP. Any difference is rectified by the diodes and fed to Q1 , which lights the LED. That will not happen until and unless it clips.
MOST power amp stages are non inverting, but if you happen to get one that inverts then R1 an R3 are chosen to null right there and the OP AMP only ne eds serve as a buffer.
The REASON you need to do this to detect clipping in an amp is because you never know what the power supply voltages are going to be as they are usual ly not regulated and they vary with line voltage, and how the varying speak er impedance reacts to the input signal.
Another way to do it, more hillbillyish, is to ust use the power supply rai ls in the amp as a reference and when the speaker voltage gets within about a volt of that then trigger something to light the LED. This also works we ll enough for some. The circuit on the back of the proverbial napkin in the picture has an added advantage of detecting if the amp is not working well with an uncooperative load, like certain amps with peizo or electrostatic tweeters, or if there is actually a fault in the amp that is not apparent t o the ears, or if the current limiting is kicking in for some reason.
The ciruit that is (somewhat) depicted does not really detect distortion in the conventional sense, it does but it is simply detecting the differecne between the input and output signal. Yes it is distortion but this is not, well, quite, the IHF method and any measurements you can take with this are not admissible in the official spec sheet.
Thanks to everyone for their helpful suggestions. I will try them all out and see if I can get the circuit to work.
I will also substitute another type of op amp before totally giving up. The simplicty appeals to me.
This looks like a slightly more sophisticated approach. It's for a single purpose. I don't really need a hi-fi type solution.
Mark Newman
From the style of the schematic, I'd guess that the magazine is Elektuur / Elektor (originally Dutch).
-- Tauno Voipio
The diodes on the inputs really bothers me. Depending on leakage is well put, but in my mind, the inputs are floating. I try to limit the number of high impedance nodes in a circuit. If a node is high impedance, there better be a good reason.
It may look more sophisticated but its not much better. I especially hate C5 which seems intended to give Q1 as hard a time as possible - I would remove it but the circuit still won't work very well.
Michael Kellett
On a sunny day (Thu, 13 Feb 2014 09:38:43 +0200) it happened Tauno Voipio wrote in :
Yes I noticed that too, and the 'lek van elektuur' could have the errata..
I'm wondering if it was initially designed for an op-amp with an appreciable bias current?
I would also recommend the OP finds better circuits although they're likely to be more complex.
-- Mike Perkins Video Solutions Ltd www.videosolutions.ltd.uk
You got that one right, especially in a built-up circuit. Of course, all it's doing is blinking a LED. ;)
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
On Thu, 13 Feb 2014 10:55:20 +1100, snipped-for-privacy@keystone.com wrote:
--- Version 4 SHEET 1 1620 1624 WIRE 384 960 384 928 WIRE 656 960 656 928 WIRE 784 960 784 928 WIRE 912 960 784 960 WIRE 1168 960 1136 960 WIRE 528 1024 528 992 WIRE 784 1024 784 960 WIRE 912 1024 880 1024 WIRE 1232 1024 1136 1024 WIRE 112 1072 -16 1072 WIRE 256 1072 208 1072 WIRE 384 1072 384 1040 WIRE 384 1072 336 1072 WIRE 464 1072 384 1072 WIRE 656 1088 656 1040 WIRE 656 1088 592 1088 WIRE 880 1088 880 1024 WIRE 912 1088 880 1088 WIRE 1360 1088 1136 1088 WIRE 112 1104 112 1072 WIRE 1168 1152 1136 1152 WIRE 1360 1152 1360 1088 WIRE 784 1168 784 1104 WIRE 880 1168 880 1088 WIRE 880 1168 784 1168 WIRE 656 1216 656 1088 WIRE 656 1216 592 1216 WIRE 1232 1216 1232 1024 WIRE 1232 1216 656 1216 WIRE 112 1232 112 1184 WIRE 208 1232 208 1072 WIRE 208 1232 112 1232 WIRE 256 1232 208 1232 WIRE 384 1232 336 1232 WIRE 464 1232 384 1232 WIRE 880 1248 880 1168 WIRE -128 1280 -128 1248 WIRE -16 1280 -16 1072 WIRE 384 1280 384 1232 WIRE 784 1280 784 1168 WIRE 112 1296 112 1232 WIRE 976 1296 944 1296 WIRE 1232 1296 1232 1216 WIRE 1232 1296 1056 1296 WIRE 1360 1296 1360 1232 WIRE 528 1312 528 1280 WIRE -128 1392 -128 1360 WIRE -96 1392 -128 1392 WIRE -128 1424 -128 1392 WIRE -16 1424 -16 1360 WIRE -16 1424 -128 1424 WIRE 112 1424 112 1376 WIRE 112 1424 -16 1424 WIRE 384 1424 384 1360 WIRE 384 1424 112 1424 WIRE 784 1424 784 1344 WIRE 784 1424 384 1424 WIRE 880 1424 880 1344 WIRE 880 1424 784 1424 WIRE 1360 1424 1360 1360 WIRE 1360 1424 880 1424 WIRE -128 1488 -128 1424 FLAG -128 1488 0 FLAG -128 1248 +12 FLAG -96 1392 0V FLAG 528 992 0V FLAG 528 1312 +12 FLAG 656 928 +12 FLAG 384 928 +12 FLAG 1168 1152 +12 FLAG 1168 960 0V FLAG 784 928 +12 SYMBOL voltage -16 1264 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value SINE(0 1 10) SYMATTR InstName V1 SYMBOL res 640 944 R0 SYMATTR InstName R1 SYMATTR Value 10k SYMBOL voltage -128 1264 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value 12 SYMATTR InstName V2 SYMBOL res 368 1264 R0 SYMATTR InstName R2 SYMATTR Value 100k SYMBOL res 352 1216 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 100k SYMBOL Comparators\\LT6700-1 528 1152 M180 WINDOW 0 71 -115 Left 2 WINDOW 3 18 -152 Left 2 SYMATTR InstName U1 SYMBOL res 368 944 R0 SYMATTR InstName R4 SYMATTR Value 10k SYMBOL res 352 1056 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 1000 SYMBOL Misc\\NE555 1024 1056 M0 SYMATTR InstName U2 SYMBOL res 800 1008 M0 SYMATTR InstName R6 SYMATTR Value 1meg SYMBOL cap 800 1280 M0 SYMATTR InstName C1 SYMATTR Value 220n SYMBOL res 960 1280 M90 WINDOW 0 65 59 VBottom 2 WINDOW 3 68 59 VTop 2 SYMATTR InstName R7 SYMATTR Value 10k SYMBOL pnp 944 1344 R180 WINDOW 0 78 34 Left 2 WINDOW 3 60 64 Left 2 SYMATTR InstName Q1 SYMATTR Value 2N3906 SYMBOL res 1376 1248 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R8 SYMATTR Value 430 SYMBOL LED 1344 1296 R0 WINDOW 0 -27 -1 Left 2 WINDOW 3 -10 64 Left 2 SYMATTR InstName D1 SYMBOL res 128 1392 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R9 SYMATTR Value 10k SYMBOL res 128 1200 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R10 SYMATTR Value 10 TEXT 360 1200 Left 2 ;+peak TEXT 360 1104 Left 2 ;- peak TEXT 120 1456 Right 2 !.tran 0 1 0 startup uic TEXT 112 1232 Left 5 ;< TEXT -40 1032 Left 2 ;R9R10 = 10k pot TEXT 440 848 Left 2 ;PEAK DETECTOR TEXT 920 848 Left 2 ;RETRIGGERABLE TEXT 952 880 Left 2 ;ONE-SHOT TEXT 1304 1360 Left 2 ;LE TEXT 144 1456 Left 2 ;PEAK DETECTOR AND INDICATOR TEXT 144 1488 Left 2 ;JOHN FIELDS, 13 FEB 2014 TEXT 400 816 Left 2 ;POSITIVE AND NEGATIVE
(Snip)
Thanks John. This looks rock solid. I'll order in the LT part.
One day I hope to be able to design like this.
Mark Newman
-- Thanks for the compliment. :-) I used the Linear part because it was convenient, but an LM393 and a reference made from a voltage divider across the rails would work as well and would be substantially less pricey. Also, if you're going to build these for stereo, you could use an LM339 and a (7)556 and keep your chip count to two.
On Thu, 13 Feb 2014 15:04:06 -0600, John Fields wrote:
--- Looks like the transistor can go away:
Version 4 SHEET 1 1620 1624 WIRE 384 960 384 928 WIRE 656 960 656 928 WIRE 880 960 880 928 WIRE 1008 960 880 960 WIRE 1264 960 1232 960 WIRE 528 1024 528 992 WIRE 1008 1024 976 1024 WIRE 1328 1024 1232 1024 WIRE 880 1040 880 960 WIRE 112 1072 -16 1072 WIRE 256 1072 208 1072 WIRE 384 1072 384 1040 WIRE 384 1072 336 1072 WIRE 464 1072 384 1072 WIRE 656 1088 656 1040 WIRE 656 1088 592 1088 WIRE 976 1088 976 1024 WIRE 1008 1088 976 1088 WIRE 1456 1088 1232 1088 WIRE 112 1104 112 1072 WIRE 1264 1152 1232 1152 WIRE 1456 1152 1456 1088 WIRE 656 1216 656 1088 WIRE 656 1216 592 1216 WIRE 688 1216 656 1216 WIRE 768 1216 752 1216 WIRE 880 1216 880 1120 WIRE 880 1216 848 1216 WIRE 112 1232 112 1184 WIRE 208 1232 208 1072 WIRE 208 1232 112 1232 WIRE 256 1232 208 1232 WIRE 384 1232 336 1232 WIRE 464 1232 384 1232 WIRE 880 1232 880 1216 WIRE 976 1232 976 1088 WIRE 976 1232 880 1232 WIRE 1328 1232 1328 1024 WIRE 1328 1232 976 1232 WIRE -128 1280 -128 1248 WIRE -16 1280 -16 1072 WIRE 112 1296 112 1232 WIRE 384 1296 384 1232 WIRE 880 1296 880 1232 WIRE 1456 1296 1456 1232 WIRE 528 1312 528 1280 WIRE -128 1392 -128 1360 WIRE -96 1392 -128 1392 WIRE -128 1424 -128 1392 WIRE -16 1424 -16 1360 WIRE -16 1424 -128 1424 WIRE 112 1424 112 1376 WIRE 112 1424 -16 1424 WIRE 384 1424 384 1376 WIRE 384 1424 112 1424 WIRE 880 1424 880 1360 WIRE 880 1424 384 1424 WIRE 1456 1424 1456 1360 WIRE 1456 1424 880 1424 WIRE -128 1488 -128 1424 FLAG -128 1488 0 FLAG -128 1248 +12 FLAG -96 1392 0V FLAG 528 992 0V FLAG 528 1312 +12 FLAG 656 928 +12 FLAG 384 928 +12 FLAG 1264 1152 +12 FLAG 1264 960 0V FLAG 880 928 +12 SYMBOL voltage -16 1264 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value SINE(0 1 10) SYMATTR InstName V1 SYMBOL res 640 944 R0 SYMATTR InstName R1 SYMATTR Value 10k SYMBOL voltage -128 1264 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value 12 SYMATTR InstName V2 SYMBOL res 368 1280 R0 SYMATTR InstName R2 SYMATTR Value 100k SYMBOL res 352 1216 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 100k SYMBOL Comparators\\LT6700-1 528 1152 M180 WINDOW 0 71 -115 Left 2 WINDOW 3 18 -152 Left 2 SYMATTR InstName U1 SYMBOL res 368 944 R0 SYMATTR InstName R4 SYMATTR Value 10k SYMBOL res 352 1056 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 1000 SYMBOL Misc\\NE555 1120 1056 M0 SYMATTR InstName U2 SYMBOL res 896 1024 M0 SYMATTR InstName R6 SYMATTR Value 1meg SYMBOL cap 896 1296 M0 SYMATTR InstName C1 SYMATTR Value 220n SYMBOL res 1472 1248 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R8 SYMATTR Value 430 SYMBOL LED 1440 1296 R0 WINDOW 0 -27 -1 Left 2 WINDOW 3 -10 64 Left 2 SYMATTR InstName D1 SYMBOL res 128 1392 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R9 SYMATTR Value 10k SYMBOL res 128 1200 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R10 SYMATTR Value 10 SYMBOL diode 752 1200 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName D2 SYMATTR Value 1N4148 SYMBOL res 864 1200 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R7 SYMATTR Value 100 TEXT 360 1200 Left 2 ;+peak TEXT 360 1104 Left 2 ;- peak TEXT 120 1456 Right 2 !.tran 0 1 0 startup uic TEXT 112 1232 Left 5 ;< TEXT -40 1032 Left 2 ;R9R10 = 10k pot TEXT 440 848 Left 2 ;PEAK DETECTOR TEXT 1016 848 Left 2 ;RETRIGGERABLE TEXT 1048 880 Left 2 ;ONE-SHOT TEXT 1400 1360 Left 2 ;LE TEXT 144 1456 Left 2 ;PEAK DETECTOR AND INDICATOR , REV A TEXT 144 1488 Left 2 ;JOHN FIELDS, 13 FEB 2014 TEXT 400 816 Left 2 ;POSITIVE AND NEGATIVE
Thanks John. I will think of you every time I see that lttle clear plastic thing flash ;-)
Mark
On Fri, 14 Feb 2014 11:18:52 +1100, snipped-for-privacy@keystone.com wrote:
--- :-)
OK, here ya go...
It's getting exciting now!
One chip, an LM339N from Digi-Key at about 60 cents for thru-hole onesies at:
instead of the pricey LTC dual comparator and the 555.
Substitute the four LM 339 comparators for the four LT1017s on the schematic and you should be good to go, for peanuts.
Version 4 SHEET 1 1620 1624 WIRE 288 864 -224 864 WIRE 384 864 288 864 WIRE 608 864 384 864 WIRE 848 864 608 864 WIRE 944 864 848 864 WIRE 1024 864 944 864 WIRE 1168 864 1104 864 WIRE 288 912 288 864 WIRE 384 912 384 864 WIRE 608 912 608 864 WIRE 848 912 848 864 WIRE 944 912 944 864 WIRE 1168 960 1168 864 WIRE 160 1040 112 1040 WIRE 288 1040 288 992 WIRE 288 1040 240 1040 WIRE 464 1040 288 1040 WIRE 944 1040 944 992 WIRE 1008 1040 944 1040 WIRE 608 1056 608 992 WIRE 608 1056 528 1056 WIRE 1168 1056 1168 1024 WIRE 1168 1056 1072 1056 WIRE 16 1072 -112 1072 WIRE 384 1072 384 992 WIRE 464 1072 384 1072 WIRE 848 1072 848 992 WIRE 1008 1072 848 1072 WIRE 16 1104 16 1072 WIRE 384 1200 384 1072 WIRE 464 1200 384 1200 WIRE 944 1200 944 1040 WIRE 1008 1200 944 1200 WIRE 608 1216 608 1056 WIRE 608 1216 528 1216 WIRE 640 1216 608 1216 WIRE 736 1216 704 1216 WIRE 848 1216 848 1072 WIRE 848 1216 816 1216 WIRE 1168 1216 1168 1056 WIRE 1168 1216 1072 1216 WIRE 16 1232 16 1184 WIRE 112 1232 112 1040 WIRE 112 1232 16 1232 WIRE 160 1232 112 1232 WIRE 288 1232 240 1232 WIRE 464 1232 288 1232 WIRE 848 1232 848 1216 WIRE 1008 1232 848 1232 WIRE -224 1248 -224 864 WIRE -192 1248 -224 1248 WIRE -224 1280 -224 1248 WIRE -112 1280 -112 1072 WIRE 16 1296 16 1232 WIRE 288 1296 288 1232 WIRE 384 1296 384 1200 WIRE 848 1296 848 1232 WIRE 944 1296 944 1200 WIRE -224 1392 -224 1360 WIRE -192 1392 -224 1392 WIRE -224 1424 -224 1392 WIRE -112 1424 -112 1360 WIRE -112 1424 -224 1424 WIRE 16 1424 16 1376 WIRE 16 1424 -112 1424 WIRE 288 1424 288 1376 WIRE 288 1424 16 1424 WIRE 384 1424 384 1376 WIRE 384 1424 288 1424 WIRE 848 1424 848 1360 WIRE 848 1424 384 1424 WIRE 944 1424 944 1376 WIRE 944 1424 848 1424 WIRE -224 1488 -224 1424 FLAG -224 1488 0 FLAG -192 1248 +12 FLAG 496 1184 0V FLAG 496 1024 0V FLAG 496 1248 +12 FLAG 496 1088 +12 FLAG 1040 1184 +12 FLAG 1040 1248 0V FLAG -192 1392 0V FLAG 1040 1024 +12 FLAG 1040 1088 0V SYMBOL voltage -112 1264 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value SINE(0 1 10) SYMATTR InstName V1 SYMBOL res 592 896 R0 SYMATTR InstName R1 SYMATTR Value 10k SYMBOL voltage -224 1264 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value 12 SYMATTR InstName V2 SYMBOL res 272 1280 R0 SYMATTR InstName R2 SYMATTR Value 100k SYMBOL res 256 1216 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 100k SYMBOL res 272 896 R0 SYMATTR InstName R4 SYMATTR Value 10k SYMBOL res 256 1024 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 1000 SYMBOL res 864 896 M0 SYMATTR InstName R6 SYMATTR Value 1meg SYMBOL cap 864 1296 M0 SYMATTR InstName C1 SYMATTR Value 220n SYMBOL res 1008 880 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R8 SYMATTR Value 430 SYMBOL LED 1152 960 R0 WINDOW 0 -27 -1 Left 2 WINDOW 3 -10 64 Left 2 SYMATTR InstName D1 SYMBOL res 32 1392 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R9 SYMATTR Value 10k SYMBOL res 32 1200 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R10 SYMATTR Value 10 SYMBOL diode 704 1200 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName D2 SYMATTR Value 1N4148 SYMBOL res 832 1200 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R7 SYMATTR Value 100 SYMBOL Comparators\\LT1017 1040 1216 R0 SYMATTR InstName U2 SYMBOL res 960 896 M0 WINDOW 0 -61 35 Left 2 WINDOW 3 -73 73 Left 2 SYMATTR InstName R11 SYMATTR Value 1meg SYMBOL res 960 1280 M0 WINDOW 0 -62 27 Left 2 WINDOW 3 -78 61 Left 2 SYMATTR InstName R12 SYMATTR Value 2meg SYMBOL Comparators\\LT1017 496 1056 M180 SYMATTR InstName U3 SYMBOL Comparators\\LT1017 496 1216 M180 SYMATTR InstName U4 SYMBOL res 368 1280 R0 SYMATTR InstName R13 SYMATTR Value 3400 SYMBOL res 368 896 R0 SYMATTR InstName R14 SYMATTR Value 100k SYMBOL Comparators\\LT1017 1040 1056 R0 SYMATTR InstName U1 TEXT 392 1256 Left 2 ;+peak TEXT 392 1024 Left 2 ;- peak TEXT -64 1456 Right 2 !.tran 0 1 0 uic TEXT 16 1232 Left 5 ;< TEXT -136 1032 Left 2 ;R9R10 = 10k pot TEXT 368 808 Left 2 ;PEAK DETECTOR TEXT 944 776 Left 2 ;RETRIGGERABLE TEXT 968 808 Left 2 ;ONE-SHOT TEXT 1112 1024 Left 2 ;LE TEXT -40 1456 Left 2 ;PEAK DETECTOR AND INDICATOR , REV B TEXT 488 1456 Left 2 ;JOHN FIELDS, 13 FEB 2014 TEXT 336 776 Left 2 ;POSITIVE AND NEGATIVE
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