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#1
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I am still developing my abilities and find myself all too often
struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. DC coupled with frequency response DC to 20KHz Input signal level 1-2V 4 to 12 volts single supply Low power DIP op amp, suited to battery operation if required Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) Other specs are non-critical. Are any of these, such as the wide supply range, inherently contradictory to a predominantly fixed value circuit? Any help would be very much appreciated. Trev Morton |
#2
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On Thu, 22 Mar 2007 21:35:33 +1100, Trevor Morton wrote:
I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. DC coupled with frequency response DC to 20KHz Input signal level 1-2V 4 to 12 volts single supply Low power DIP op amp, suited to battery operation if required Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) You've just described the National LM386, as if you'd copied that off the data sheet: http://www.national.com/ds/LM/LM386.pdf Have Fun! Rich |
#3
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I thought the LM386 was an audio amp (not to DC), but had a try anyway
with a 5Hz squarewave. Distortion was pretty bad. Also, regardless of frequency, I only get 1V swing out with 6V in. It is supposed to have a built-in gain of 20. This I don't understand. Getting back to my original post. Is it possible to have a single op amp design that will cover the variation in supply voltage and load described? Thanks for any advice. Trevor Morton On Thu, 22 Mar 2007 23:46:38 GMT, Rich Grise wrote: On Thu, 22 Mar 2007 21:35:33 +1100, Trevor Morton wrote: I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. DC coupled with frequency response DC to 20KHz Input signal level 1-2V 4 to 12 volts single supply Low power DIP op amp, suited to battery operation if required Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) You've just described the National LM386, as if you'd copied that off the data sheet: http://www.national.com/ds/LM/LM386.pdf Have Fun! Rich |
#4
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![]() Trevor Morton wrote: I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. DC coupled with frequency response DC to 20KHz Input signal level 1-2V 4 to 12 volts single supply Low power DIP op amp, suited to battery operation if required Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) What you're desribing is an amplifier. NOT an op-amp. Graham |
#5
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On Fri, 23 Mar 2007 14:11:39 +0000, Eeyore
wrote: Trevor Morton wrote: I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. DC coupled with frequency response DC to 20KHz Input signal level 1-2V 4 to 12 volts single supply Low power DIP op amp, suited to battery operation if required Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) What you're desribing is an amplifier. NOT an op-amp. --- Funny, it seems that's what he was asking for in his second sentence. -- JF |
#6
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![]() John Fields wrote: Eeyore wrote: Trevor Morton wrote: I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. DC coupled with frequency response DC to 20KHz Input signal level 1-2V 4 to 12 volts single supply Low power DIP op amp, suited to battery operation if required Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) What you're desribing is an amplifier. NOT an op-amp. --- Funny, it seems that's what he was asking for in his second sentence. So why "op amp" in the thread title and above "Low power DIP op amp....." ? I suspect here may be some confusion in the OP's mind. Graham |
#7
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On Fri, 23 Mar 2007 15:17:15 +0000, Eeyore
wrote: John Fields wrote: Eeyore wrote: Trevor Morton wrote: I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. DC coupled with frequency response DC to 20KHz Input signal level 1-2V 4 to 12 volts single supply Low power DIP op amp, suited to battery operation if required Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) What you're desribing is an amplifier. NOT an op-amp. --- Funny, it seems that's what he was asking for in his second sentence. So why "op amp" in the thread title and above "Low power DIP op amp....." ? I suspect here may be some confusion in the OP's mind. --- I see no confusion; he seems to know exactly what he wants. The "Low power DIP op amp" is what he'll use to drive the output transistor, the combination being the "all purpose" amplifier he wants, while "All purpose SS op amp" is less clumsy than "All purpose SS op amp amp." -- JF |
#8
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![]() John Fields wrote: Eeyore wrote: John Fields wrote: Eeyore wrote: Trevor Morton wrote: I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. DC coupled with frequency response DC to 20KHz Input signal level 1-2V 4 to 12 volts single supply Low power DIP op amp, suited to battery operation if required Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) What you're desribing is an amplifier. NOT an op-amp. --- Funny, it seems that's what he was asking for in his second sentence. So why "op amp" in the thread title and above "Low power DIP op amp....." ? I suspect here may be some confusion in the OP's mind. --- I see no confusion; he seems to know exactly what he wants. The "Low power DIP op amp" is what he'll use to drive the output transistor, the combination being the "all purpose" amplifier he wants, while "All purpose SS op amp" is less clumsy than "All purpose SS op amp amp." You reckon he only needs *one* output transistor ? Graham |
#9
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![]() Trevor Morton wrote: I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. Is there any particular reson you want to use discretes for the output stage ? You'll increase complexity lots. DC coupled with frequency response DC to 20KHz Do you mean audio ? Input signal level 1-2V 4 to 12 volts single supply If it's a single supply you'll have to AC couple the signal ! Unless you want a bridge tied load of course (more complicated). Low power DIP op amp, suited to battery operation if required Well, power dissipation is likely to be predominantly determined by any quiesent current in the output stage (to avoid cross-over distortion) actually. Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) Other specs are non-critical. Are any of these, such as the wide supply range, inherently contradictory to a predominantly fixed value circuit? Any help would be very much appreciated. The simplest best bet might be to look at some car audio amplifier chips. Graham |
#10
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![]() Trevor Morton wrote: I thought the LM386 was an audio amp (not to DC), but had a try anyway with a 5Hz squarewave. Distortion was pretty bad. Also, regardless of frequency, I only get 1V swing out with 6V in. It is supposed to have a built-in gain of 20. This I don't understand. You have to tie a cap from ground to one of the gain set pins to get that. Graham |
#11
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On Fri, 23 Mar 2007 16:37:48 +0000, Eeyore
wrote: John Fields wrote: Eeyore wrote: John Fields wrote: Eeyore wrote: Trevor Morton wrote: I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. DC coupled with frequency response DC to 20KHz Input signal level 1-2V 4 to 12 volts single supply Low power DIP op amp, suited to battery operation if required Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) What you're desribing is an amplifier. NOT an op-amp. --- Funny, it seems that's what he was asking for in his second sentence. So why "op amp" in the thread title and above "Low power DIP op amp....." ? I suspect here may be some confusion in the OP's mind. --- I see no confusion; he seems to know exactly what he wants. The "Low power DIP op amp" is what he'll use to drive the output transistor, the combination being the "all purpose" amplifier he wants, while "All purpose SS op amp" is less clumsy than "All purpose SS op amp amp." You reckon he only needs *one* output transistor ? --- That's what he wants. Can't you do it? -- JF |
#12
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On Fri, 23 Mar 2007 13:55:19 -0500, John Fields wrote:
On Fri, 23 Mar 2007 16:37:48 +0000, Eeyore John Fields wrote: Eeyore wrote: John Fields wrote: Eeyore wrote: Trevor Morton wrote: I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. DC coupled with frequency response DC to 20KHz Input signal level 1-2V 4 to 12 volts single supply Low power DIP op amp, suited to battery operation if required Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) What you're desribing is an amplifier. NOT an op-amp. Funny, it seems that's what he was asking for in his second sentence. So why "op amp" in the thread title and above "Low power DIP op amp....." ? I suspect here may be some confusion in the OP's mind. I see no confusion; he seems to know exactly what he wants. The "Low power DIP op amp" is what he'll use to drive the output transistor, the combination being the "all purpose" amplifier he wants, while "All purpose SS op amp" is less clumsy than "All purpose SS op amp amp." You reckon he only needs *one* output transistor ? That's what he wants. Can't you do it? Nat Semi has a pretty cool app note: http://www.eetkorea.com/ARTICLES/200...6_AMD_AN03.PDF Cheers! Rich |
#13
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I am sorry if my original post caused confusion. Yes, I am looking for
an op amp because of the DC requirement. The LM386 I tried to no avail. Phrasing it another way, why is there no predefined op amp/Darlington configuration, or off-the-shelf power op amp, that can do the all same things as the LM386 does with audio, but down to DC? Single supply Wide supplyvoltage range DC coupling Easily variable gain Low power Etc. At first, I thought such specs might be mutually exclusive. However, if there are such design limitations, they seem to be receeding fast. For example, there is the "new" OPA569, rated at 2A. It meets all my requirements except it only operates up to 5.5V. I need a range of 4 to 12V. http://focus.ti.com/docs/prod/folders/print/opa569.html Can someone explain, why can't something like this be done with a CA3130 and a couple of transistors. Trevor Morton On Fri, 23 Mar 2007 17:23:09 +0000, Eeyore wrote: Trevor Morton wrote: I am still developing my abilities and find myself all too often struggling with op amp design. Can anyone here suggest an "all purpose" amplifier built around a readily available op amp and transistor follower that will operate within the specifications below? Preferably without changes in componentry except to upgrade the power transistor depending upon load requirements. Is there any particular reson you want to use discretes for the output stage ? You'll increase complexity lots. DC coupled with frequency response DC to 20KHz Do you mean audio ? Input signal level 1-2V 4 to 12 volts single supply If it's a single supply you'll have to AC couple the signal ! Unless you want a bridge tied load of course (more complicated). Low power DIP op amp, suited to battery operation if required Well, power dissipation is likely to be predominantly determined by any quiesent current in the output stage (to avoid cross-over distortion) actually. Variable gain, unity to 10 via trimpot (dependent on rail V) Swing as close to rail as practical without using a rail-to-rail amp Drive resistive load 20 to 200 ohms (dependent on power transistor used.) Other specs are non-critical. Are any of these, such as the wide supply range, inherently contradictory to a predominantly fixed value circuit? Any help would be very much appreciated. The simplest best bet might be to look at some car audio amplifier chips. Graham |
#14
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On Sat, 24 Mar 2007 07:48:15 +1100, Trevor Morton
wrote: I am sorry if my original post caused confusion. Yes, I am looking for an op amp because of the DC requirement. The LM386 I tried to no avail. Phrasing it another way, why is there no predefined op amp/Darlington configuration, or off-the-shelf power op amp, that can do the all same things as the LM386 does with audio, but down to DC? Single supply Wide supplyvoltage range DC coupling Easily variable gain Low power Etc. At first, I thought such specs might be mutually exclusive. However, if there are such design limitations, they seem to be receeding fast. For example, there is the "new" OPA569, rated at 2A. It meets all my requirements except it only operates up to 5.5V. I need a range of 4 to 12V. http://focus.ti.com/docs/prod/folders/print/opa569.html Can someone explain, why can't something like this be done with a CA3130 and a couple of transistors. --- Please bottom post. The main reason you can't get what you want is because you're specifying a single supply and DC coupling and expecting an output which can swing negative. For example, this circuit: Version 4 SHEET 1 880 680 WIRE -192 64 -416 64 WIRE -80 64 -112 64 WIRE 64 64 -80 64 WIRE 336 64 144 64 WIRE -80 192 -80 64 WIRE -48 192 -80 192 WIRE 64 208 16 208 WIRE 176 208 144 208 WIRE -240 224 -272 224 WIRE -192 224 -240 224 WIRE -80 224 -112 224 WIRE -48 224 -80 224 WIRE 240 272 240 256 WIRE 336 272 336 64 WIRE 336 272 240 272 WIRE -416 288 -416 64 WIRE -240 288 -240 224 WIRE -80 288 -80 224 WIRE 240 304 240 272 WIRE -416 416 -416 368 WIRE -240 416 -240 368 WIRE -240 416 -416 416 WIRE -80 416 -80 368 WIRE -80 416 -240 416 WIRE -16 416 -16 240 WIRE -16 416 -80 416 WIRE 240 416 240 384 WIRE 240 416 -16 416 WIRE -416 480 -416 416 FLAG -416 480 0 FLAG -272 224 +12V FLAG 240 160 +12V FLAG -16 176 +12V SYMBOL Opamps\\LT1055 -16 144 R0 WINDOW 0 30 88 Left 0 WINDOW 3 27 117 Left 0 SYMATTR InstName U1 SYMBOL npn 176 160 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL res 224 288 R0 SYMATTR InstName R2 SYMATTR Value 20 SYMBOL res -96 272 R0 SYMATTR InstName R3 SYMATTR Value 10K SYMBOL res -96 208 R90 WINDOW 0 94 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R4 SYMATTR Value 10K SYMBOL voltage -240 272 R0 WINDOW 0 -50 100 Left 0 WINDOW 3 24 104 Invisible 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 12 SYMBOL voltage -416 272 R0 WINDOW 0 -50 100 Left 0 WINDOW 3 24 104 Invisible 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value SINE(6 .1 10) SYMBOL res -96 48 R90 WINDOW 0 -36 49 VBottom 0 WINDOW 3 -35 52 VTop 0 SYMATTR InstName R5 SYMATTR Value 1K SYMBOL res 160 192 R90 WINDOW 0 -41 58 VBottom 0 WINDOW 3 -37 56 VTop 0 SYMATTR InstName R6 SYMATTR Value 1K SYMBOL res 160 48 R90 WINDOW 0 -39 56 VBottom 0 WINDOW 3 -34 57 VTop 0 SYMATTR InstName R1 SYMATTR Value 10K TEXT -396 450 Left 0 !.tran 1 uic will do what you want, but because of the single supply and no capacitor rule, the input signal must be offset and the output signal will swing about a DC value, which will waste power in the load as well as in the single (which is what you asked for) output transistor. The circuit list, above, is for LTSPICE, and if you don't have a copy you can download one, free, at: http://www.linear.com/designtools/software/ One caveat: the output transistor I used can't dissipate the power needed to feed the 20 ohm load shown, but I didn't want to spend a lot of time looking for the right one this early in the game. -- JF |
#15
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![]() "Eeysore Trevor Morton wrote: I thought the LM386 was an audio amp (not to DC), but had a try anyway with a 5Hz squarewave. Distortion was pretty bad. Also, regardless of frequency, I only get 1V swing out with 6V in. It is supposed to have a built-in gain of 20. This I don't understand. You have to tie a cap from ground to one of the gain set pins to get that. ** No you don't - fool. See the very first schem under Typical Applications. ....... Phil |
#16
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![]() "Trevor Morton" I thought the LM386 was an audio amp (not to DC), but had a try anyway with a 5Hz squarewave. Distortion was pretty bad. Also, regardless of frequency, I only get 1V swing out with 6V in. It is supposed to have a built-in gain of 20. This I don't understand. ** Try again - you got it fouled up somehow. With a 4 volt supply, square wave drive and 33 ohm load ( no coupling cap), the output is a clean. 2.6 volt p-p square wave at *any* frequency up to 20kHz. With a 12 volt supply, same set up as above, the output swing is 10 volt p-p. Same p-p swings apply to a sine wave input as well. BTW Make sure your input signal does not have a DC offset. ........ Phil |
#17
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On Fri, 23 Mar 2007 18:13:20 -0500, John Fields
wrote: On Sat, 24 Mar 2007 07:48:15 +1100, Trevor Morton wrote: I am sorry if my original post caused confusion. Yes, I am looking for an op amp because of the DC requirement. The LM386 I tried to no avail. Phrasing it another way, why is there no predefined op amp/Darlington configuration, or off-the-shelf power op amp, that can do the all same things as the LM386 does with audio, but down to DC? Single supply Wide supplyvoltage range DC coupling Easily variable gain Low power Etc. At first, I thought such specs might be mutually exclusive. However, if there are such design limitations, they seem to be receeding fast. For example, there is the "new" OPA569, rated at 2A. It meets all my requirements except it only operates up to 5.5V. I need a range of 4 to 12V. http://focus.ti.com/docs/prod/folders/print/opa569.html Can someone explain, why can't something like this be done with a CA3130 and a couple of transistors. --- Please bottom post. The main reason you can't get what you want is because you're specifying a single supply and DC coupling and expecting an output which can swing negative. For example, this circuit: Version 4 SHEET 1 880 680 WIRE -192 64 -416 64 WIRE -80 64 -112 64 WIRE 64 64 -80 64 WIRE 336 64 144 64 WIRE -80 192 -80 64 WIRE -48 192 -80 192 WIRE 64 208 16 208 WIRE 176 208 144 208 WIRE -240 224 -272 224 WIRE -192 224 -240 224 WIRE -80 224 -112 224 WIRE -48 224 -80 224 WIRE 240 272 240 256 WIRE 336 272 336 64 WIRE 336 272 240 272 WIRE -416 288 -416 64 WIRE -240 288 -240 224 WIRE -80 288 -80 224 WIRE 240 304 240 272 WIRE -416 416 -416 368 WIRE -240 416 -240 368 WIRE -240 416 -416 416 WIRE -80 416 -80 368 WIRE -80 416 -240 416 WIRE -16 416 -16 240 WIRE -16 416 -80 416 WIRE 240 416 240 384 WIRE 240 416 -16 416 WIRE -416 480 -416 416 FLAG -416 480 0 FLAG -272 224 +12V FLAG 240 160 +12V FLAG -16 176 +12V SYMBOL Opamps\\LT1055 -16 144 R0 WINDOW 0 30 88 Left 0 WINDOW 3 27 117 Left 0 SYMATTR InstName U1 SYMBOL npn 176 160 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL res 224 288 R0 SYMATTR InstName R2 SYMATTR Value 20 SYMBOL res -96 272 R0 SYMATTR InstName R3 SYMATTR Value 10K SYMBOL res -96 208 R90 WINDOW 0 94 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R4 SYMATTR Value 10K SYMBOL voltage -240 272 R0 WINDOW 0 -50 100 Left 0 WINDOW 3 24 104 Invisible 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 12 SYMBOL voltage -416 272 R0 WINDOW 0 -50 100 Left 0 WINDOW 3 24 104 Invisible 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value SINE(6 .1 10) SYMBOL res -96 48 R90 WINDOW 0 -36 49 VBottom 0 WINDOW 3 -35 52 VTop 0 SYMATTR InstName R5 SYMATTR Value 1K SYMBOL res 160 192 R90 WINDOW 0 -41 58 VBottom 0 WINDOW 3 -37 56 VTop 0 SYMATTR InstName R6 SYMATTR Value 1K SYMBOL res 160 48 R90 WINDOW 0 -39 56 VBottom 0 WINDOW 3 -34 57 VTop 0 SYMATTR InstName R1 SYMATTR Value 10K TEXT -396 450 Left 0 !.tran 1 uic will do what you want, but because of the single supply and no capacitor rule, the input signal must be offset and the output signal will swing about a DC value, which will waste power in the load as well as in the single (which is what you asked for) output transistor. The circuit list, above, is for LTSPICE, and if you don't have a copy you can download one, free, at: http://www.linear.com/designtools/software/ One caveat: the output transistor I used can't dissipate the power needed to feed the 20 ohm load shown, but I didn't want to spend a lot of time looking for the right one this early in the game. --- This is better: Version 4 SHEET 1 880 680 WIRE -16 -32 -336 -32 WIRE 240 -32 -16 -32 WIRE -448 0 -480 0 WIRE -272 0 -368 0 WIRE -336 32 -336 -32 WIRE -608 48 -640 48 WIRE -480 48 -480 0 WIRE -480 48 -528 48 WIRE -368 48 -480 48 WIRE -272 64 -272 0 WIRE -272 64 -304 64 WIRE -208 64 -272 64 WIRE -80 64 -128 64 WIRE 64 64 -80 64 WIRE 272 64 144 64 WIRE -368 80 -480 80 WIRE -240 160 -432 160 WIRE -16 160 -16 -32 WIRE -16 160 -240 160 WIRE 240 160 240 -32 WIRE -432 192 -432 160 WIRE -16 208 -16 160 WIRE -80 224 -80 64 WIRE -48 224 -80 224 WIRE 64 240 16 240 WIRE 192 240 144 240 WIRE -240 256 -240 160 WIRE -192 256 -240 256 WIRE -80 256 -112 256 WIRE -48 256 -80 256 WIRE 240 272 240 256 WIRE 272 272 272 64 WIRE 272 272 240 272 WIRE -480 304 -480 80 WIRE -432 304 -432 272 WIRE -432 304 -480 304 WIRE -640 320 -640 48 WIRE -432 320 -432 304 WIRE -240 320 -240 256 WIRE -80 320 -80 256 WIRE 240 320 240 272 WIRE -640 448 -640 400 WIRE -432 448 -432 400 WIRE -432 448 -640 448 WIRE -336 448 -336 96 WIRE -336 448 -432 448 WIRE -240 448 -240 400 WIRE -240 448 -336 448 WIRE -80 448 -80 400 WIRE -80 448 -240 448 WIRE -16 448 -16 272 WIRE -16 448 -80 448 WIRE 240 448 240 400 WIRE 240 448 -16 448 WIRE -640 512 -640 448 FLAG -640 512 0 SYMBOL res -96 304 R0 WINDOW 0 -40 46 Left 0 WINDOW 3 -47 77 Left 0 SYMATTR InstName R3 SYMATTR Value 10K SYMBOL res -96 240 R90 WINDOW 0 -33 58 VBottom 0 WINDOW 3 -33 59 VTop 0 SYMATTR InstName R4 SYMATTR Value 10k SYMBOL voltage -240 304 R0 WINDOW 0 -50 100 Left 0 WINDOW 3 24 104 Invisible 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 12 SYMBOL voltage -640 304 R0 WINDOW 0 -50 100 Left 0 WINDOW 3 24 104 Invisible 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value SINE(0 .4 10) SYMBOL res -112 48 R90 WINDOW 0 -36 49 VBottom 0 WINDOW 3 -35 52 VTop 0 SYMATTR InstName R5 SYMATTR Value 1K SYMBOL res 160 224 R90 WINDOW 0 -27 57 VBottom 0 WINDOW 3 -26 56 VTop 0 SYMATTR InstName R6 SYMATTR Value 1K SYMBOL res 160 48 R90 WINDOW 0 -39 56 VBottom 0 WINDOW 3 -34 57 VTop 0 SYMATTR InstName R1 SYMATTR Value 10K SYMBOL res -352 -16 R90 WINDOW 0 -36 54 VBottom 0 WINDOW 3 -29 58 VTop 0 SYMATTR InstName R7 SYMATTR Value 10k SYMBOL res -512 32 R90 WINDOW 0 -37 54 VBottom 0 WINDOW 3 -34 56 VTop 0 SYMATTR InstName R8 SYMATTR Value 10k SYMBOL res -416 288 R180 WINDOW 0 -59 74 Left 0 WINDOW 3 -51 44 Left 0 SYMATTR InstName R10 SYMATTR Value 9k SYMBOL res -448 304 R0 SYMATTR InstName R9 SYMATTR Value 3k SYMBOL nmos 192 160 R0 WINDOW 0 -34 47 Left 0 WINDOW 3 -76 -9 Left 0 SYMATTR InstName M1 SYMATTR Value IRF6635 SYMBOL Opamps\\LT1218 -336 0 R0 WINDOW 0 -76 100 Left 0 WINDOW 3 -100 126 Left 0 SYMATTR InstName U3 SYMBOL Opamps\\LT1218 -16 176 R0 WINDOW 0 32 86 Left 0 WINDOW 3 9 115 Left 0 SYMATTR InstName U1 SYMBOL res 224 304 R0 WINDOW 0 -40 46 Left 0 WINDOW 3 -36 74 Left 0 SYMATTR InstName R2 SYMATTR Value 20 TEXT -624 480 Left 0 !.tran 1 uic The source is DC coupled and ground-referred, and since you're using a single positive DC supply, the output is operating emitter-follower class A and varies about a quiescent Vcc/2. -- JF |
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