micro power square wave oscillator

[Joerg]

Mine is in the old well house, above an outside faucet. If I shut
off the ball valve from the new well and open that faucet, it drains
all the water from the pipe. No extra valves, and everything is in
plain sight, so it's obvious to almost anyone. All it cost was the PVC
tee and end cap.

How long does the air in there last?

 

[Jonathan Kirwan]

Jonathan Kirwan wrote:


That would be nice. It's so much easier to draw in LTSpice.

Yes, I agree. In fact, that is the only way I'd draw a schematic that
I intended for ASCII posting. Let's me check out a few things to make
sure I catch errors I should have known better about. (It won't help
me fix things I'm ignorant about, of course.)

Plots may not be so easily visible in ASCII. Only basic waveforms but
not glitches and such.

Well, if the glitch is simple enough I'd expect one to just expand the
data display sufficiently to make the point clear. If it is something
like an error where the context of the NTSC signal is also required,
I'd suppose that would be a bit 'difficult.' But I've seen folks here
struggling to draw up ASCII plots to make some point clear. Haven't
you?

Jon

 

[Joerg]

You could actually do it with a single gate valve
(single-pole-double-throw ;-)

Like a backwash valve? Then you must pay the pool equipment markup which
can easily exceed 1000% ...

 

[Joerg]

Yes, I agree. In fact, that is the only way I'd draw a schematic that
I intended for ASCII posting. Let's me check out a few things to make
sure I catch errors I should have known better about. (It won't help
me fix things I'm ignorant about, of course.)


Well, if the glitch is simple enough I'd expect one to just expand the
data display sufficiently to make the point clear. If it is something
like an error where the context of the NTSC signal is also required,
I'd suppose that would be a bit 'difficult.' But I've seen folks here
struggling to draw up ASCII plots to make some point clear. Haven't
you?

You can use the ASCII art character set in MS-Word for stuff like timing
diagrams. But it does use characters above 127 so it may not work for
all on Usenet.

 

[Jonathan Kirwan]

You can use the ASCII art character set in MS-Word for stuff like timing
diagrams. But it does use characters above 127 so it may not work for
all on Usenet.

Good advice. I was thinking, assuming I consider doing anything at
all, of using * and . and - and | and regular characters, generally. I
didn't want to stray into special non-ASCII characters (which are
7-bit, as you suggest.)

Jon

 

[Joerg]

I think the spring-loaded hammer-eliminator would be best, although I
wonder if they would corrode?

I've heard somewhere they last around 15 years. Good enough for me, they
aren't that expensive. But installation would be a bear here.

 

[Joerg]

Good advice. I was thinking, assuming I consider doing anything at
all, of using * and . and - and | and regular characters, generally. I
didn't want to stray into special non-ASCII characters (which are
7-bit, as you suggest.)

Yes. I believe some people get a UTF-8 error otherwise.

 

[James Arthur]

On Jul 7, 9:42 am, John Fields wrote:




Easy enough. I did it when I woke up this morning and realised that
I'd set up the circuit for 10kHz rather than the 100kHz asked for

<snip Bill's mvbr spice model>

Nice Bill. It's tough to make a multi fast because
it saturates the devices, which makes even RF
transistors slow. That's what drove me to ecl.

Nice example of a classic circuit updated to
the times.

Cheers,
James Arthur

 

[James Arthur]

James Arthur wrote:

[...]

I missed the part where we were designing a watch oscillator
with a 5-year life, 100kHz +/- 5ppm 0-40ºC. (If we wanted to
do that the lower frequency makes 2n3904s sing even sweeter

I thought we--Jim, John Fields and I--were just having some
fun with a nonsense requirement. Yeah, I could
do any and all of what you want, but that's not the
assignment.

Wanna play? Post your favorite circuit.

Ok, example:

3.3V 3.3V
| |
\ \
/ 1M /
\ 1M \
/ /
| |
| |
o-------o-------. '-------o-------o
| | | 2.2p| | |
| \ --- --- \ |
| / --- --- / |
| \ 2M |2.2p | \ 2M |
| / | | / |
| | | | | |
\| --------)---------' | |/
|-----' | -o-----|
<| '---------------' |> BFP620
| BFP620 |

GND GND
(created by AACircuit v1.28.6 beta 04/19/05www.tech-chat.de)

Forgive the lousy schematic, I am not used to these ASCII editors.
Anyhow, 3.3V is beyond the BFP620's 2.3V limit but there are similar
oens that reach there. Uses around 5uA in SPICE. Thing is, with a 2N3904
this won't work at all. It's capacitances snuff it out. Of course this
is rather hokey in terms of stray capacitance and would need the usual
"anti-RF" precautions such as ferrite beads or at least small resistors
in front of the bases.

The low capacitance of the fastest RF transistors might not be
needed here; a more ordinary transistor (MPSH10) operated at
super-low current might be good enough, cheaper, and less
likely to go 200MHz crazy.

You're right of course that the modest 2n3904 could never manage
the output swings you achieve here in that circuit at these power
levels. That's why I had to dodge around it by keeping
swings low.

BTW, your schematic looks great.

Fun.

Cheers,
James Arthur

 

[James Arthur]

James Arthur wrote:

[...]

I missed the part where we were designing a watch oscillator
with a 5-year life, 100kHz +/- 5ppm 0-40ºC. (If we wanted to
do that the lower frequency makes 2n3904s sing even sweeter
I thought we--Jim, John Fields and I--were just having some
fun with a nonsense requirement. Yeah, I could
do any and all of what you want, but that's not the
assignment.
Wanna play? Post your favorite circuit.

Ok, example:

3.3V 3.3V
| |
\ \
/ 1M /
\ 1M \
/ /
| |
| |
o-------o-------. '-------o-------o
| | | 2.2p| | |
| \ --- --- \ |
| / --- --- / |
| \ 2M |2.2p | \ 2M |
| / | | / |
| | | | | |
\| --------)---------' | |/
|-----' | -o-----|
<| '---------------' |> BFP620
| BFP620 |

GND GND
(created by AACircuit v1.28.6 beta 04/19/05www.tech-chat.de)

Forgive the lousy schematic, I am not used to these ASCII editors.
Anyhow, 3.3V is beyond the BFP620's 2.3V limit but there are similar
oens that reach there. Uses around 5uA in SPICE. Thing is, with a 2N3904
this won't work at all. It's capacitances snuff it out. Of course this
is rather hokey in terms of stray capacitance and would need the usual
"anti-RF" precautions such as ferrite beads or at least small resistors
in front of the bases.

Here's the same version, generated by a program I wrote directly from
an LTSpice schematic. No need to work with an ASCII editor:

: V+ V+
: V+ | |
: | \ \
: | / R3 / R4
: | \ 1Meg \ 1Meg
: --- / /
: - V1 | |
: --- 3.3V | |
: - +-----+-------, ,--+------+
: | | | | | | |
: | | \ | | \ |
: | | / R1 | | / R2 |
: gnd | \ 2Meg | | \ 2Meg |
: | / | | / |
: Q2 c\| | | | | |/c Q1
: PN5179 |---+ | | +----| PN5179
: e<| | | | | |>e
: | | | | | |
: | --- C1 | | --- C2 |
: | --- 2.2p | | --- 2.2p|
: | | | | | |
: gnd '-----------' | gnd
: | |
: '------'
: .tran 100u
:
: .model PN5179 NPN (Is=69.28E-18 Xti=3 Eg=1.11 Vaf=100
: + Bf=282.1 Ne=1.177 Ise=69.28E-18 Ikf=22.03m Xtb=1.5
: + Br=1.176 Nc=2 Isc=0 Ikr=0 Rc=4 Cjc=1.042p Mjc=.2468
: + Vjc=.75 Fc=.5 Cje=1.52p Mje=.3223 Vje=.75 Tr=1.588n
: + Tf=135.6p Itf=.27 Vtf=10 Xtf=30 Rb=10)

Note that everything I used is included. I could add comments and
those would be included on the ASCII version, as well. Also, boxes
and so on, too, if I'd used them to 'enhance' the schematic.

By the way, I used the PN5179 here, which is available and in stock at
Mouser and costs 8 cents each if you only buy one at a time.

http://www.mouser.com/Search/ProductDetail.aspx?qs=FITO//QgYDloC2....

Jon

Cool program Jon. And yes, I love those 2n5179s. I was visiting
the Bay area near Jameco once. The first chance I got I drove
over, walked into Jameco and bought a bunch of stuff, including
a load of PN5179s !

Cheers,
James Arthur

 

[krw]

According to plumbers the air is slowly absorbed into the water until
that type of "poor man's arrester" no longer works.

Drain the line every five or ten years. They've always worked for
me.

 

[Joerg]

Drain the line every five or ten years. They've always worked for
me.

Ok, but then you need a valve up top. Put's you close to the cost of a
real hammer arrester and after a few years it'll start leaking. And if
little kids are around they might find that read handle of the valve an
interesting "toy" ...

 

[krw]

Ok, but then you need a valve up top. Put's you close to the cost of a
real hammer arrester and after a few years it'll start leaking. And if
little kids are around they might find that read handle of the valve an
interesting "toy" ...

Never bothered with the bleeder. They just worked. I tend to use
longer ones than the store-bought (silly expensive things)
arresters. They're burried in walls, so no handles.

 

[James Arthur]

On Jul 7, 9:42 am, John Fields wrote:




Easy enough. I did it when I woke up this morning and realised that
I'd set up the circuit for 10kHz rather than the 100kHz asked for

Version 4
SHEET 1 2848 1240

<snip LTCSpice file for Bill's 100KHz mvbr with BFR92A npns>

Hmm, Google's posting delay has been >30 hours, so
I'm posting a little blind, and my post of a few days
ago answering this one of yours still hasn't shown up,
so please pardon any duplication.

Bill, that was a nice example of a classic circuit brought
up to date with modern components. Nifty.

The output has an exponential rise with about a 4 uS
time constant, partially from each collector load
resistor's having to charge its associated Ct. That
bit can be improved with the old diode isolation trick:

======
FIG. 1
======

----+--------+--< Vcc
R2 | R10 |
1M 1M
| D1 |
-||-+---|>|--+---> output
Ct2 |
|/
---| Q1
|>.
|
===
GND

Now when Q1 wants to turn off D1 allows R10 to "yank"
the output up without having to charge Ct2.


Here's an extension of that idea:

======
FIG. 2 Improved Output Stage
======

----+------+------+--< Vcc
| | |
| +----- | ---> output
R2 | R11 | |
1M 1M |
| | R10 |
| |/ 2M
-||-+----| Q10 |
Ct2 |>. |
'-----+
|
|/
--| Q1
|>.
|
===
GND

Q10 serves as a low-capacitance diode and also
as a common-base gain stage that further squares
up the output.

Risetime tau is improved to about 750 nS, and the
output now swings rail-to-rail.


======
FIG. 3 Full Schematic
======

+5v >-+----------------+------+------+
11uA | | | |
| | +----- | ---> output
R1 | R2 | R11 | |
1M 1M 1M |
| | | R10 |
| | |/ 2M
+---||--. .-||-+----| Q10 |
| Ct1 \ / Ct2 |>. |
| 1.5pF \ 1.5pF '-----+
| / \ |
\| / \ |/
Q2 |---+-' '-----------+---| Q1
.<| | | |>.
| --- C3 C4 --- |
| --- 0.68p 0.68p --- |
| | | |
=== === === ===
GND GND GND GND

(LTSpice file appended below.)

I went 0.5uA over current budget--feel free to tweak it.


Nice circuit Bill--I had fun playing with it. Thanks.

Cheers,
James Arthur

~~~~~~~~~~~~
Version 4
SHEET 1 2848 1276
WIRE -592 528 -752 528
WIRE -240 528 -592 528
WIRE -64 528 -240 528
WIRE 32 528 -64 528
WIRE -64 544 -64 528
WIRE 32 560 32 528
WIRE -592 576 -592 528
WIRE -240 592 -240 528
WIRE -752 624 -752 528
WIRE -64 656 -64 624
WIRE -592 704 -592 656
WIRE -464 704 -592 704
WIRE -384 704 -464 704
WIRE -240 704 -240 672
WIRE -240 704 -320 704
WIRE -128 704 -240 704
WIRE -464 736 -464 704
WIRE -240 736 -240 704
WIRE -752 784 -752 704
WIRE -64 784 -64 752
WIRE 32 784 32 640
WIRE 32 784 -64 784
WIRE -592 832 -592 704
WIRE 32 832 32 784
WIRE -512 880 -528 880
WIRE -464 880 -464 816
WIRE -464 880 -512 880
WIRE -448 880 -464 880
WIRE -384 880 -320 704
WIRE -320 880 -384 704
WIRE -240 880 -240 816
WIRE -240 880 -256 880
WIRE -208 880 -240 880
WIRE -32 880 -208 880
WIRE -208 912 -208 880
WIRE -512 928 -512 880
WIRE -592 1008 -592 928
WIRE -512 1008 -512 992
WIRE -512 1008 -592 1008
WIRE -208 1008 -208 976
WIRE 32 1008 32 928
WIRE 32 1008 -208 1008
WIRE -592 1040 -592 1008
WIRE 32 1040 32 1008
FLAG 32 1040 0
FLAG -592 1040 0
FLAG -752 784 0
SYMBOL RES -608 560 R0
SYMATTR InstName R1
SYMATTR Value 1meg
SYMBOL res 16 544 R0
SYMATTR InstName R10
SYMATTR Value 2meg
SYMBOL cap -384 864 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C1
SYMATTR Value 1.5p
SYMBOL cap -256 864 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value 1.5p
SYMBOL VOLTAGE -752 608 R0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL npn -32 832 R0
SYMATTR InstName Q1
SYMATTR Value BFR92A
SYMBOL npn -528 832 M0
SYMATTR InstName Q2
SYMATTR Value BFR92A
SYMBOL res -256 720 R0
SYMATTR InstName R3
SYMATTR Value 4.7meg
SYMBOL res -480 720 R0
SYMATTR InstName R4
SYMATTR Value 4.701meg
SYMBOL cap -528 928 R0
SYMATTR InstName C3
SYMATTR Value 0.68p
SYMBOL cap -224 912 R0
SYMATTR InstName C4
SYMATTR Value 0.68p
SYMBOL npn -128 656 R0
SYMATTR InstName Q10
SYMATTR Value BFR92A
SYMBOL RES -256 576 R0
WINDOW 3 30 76 Left 0
SYMATTR InstName R2
SYMATTR Value 1meg
SYMBOL RES -48 640 R180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R11
SYMATTR Value 1meg
TEXT -768 1176 Left 0 !.tran 0 150u 50u startup
TEXT -776 1112 Left 0 ;This example schematic is supplied for
informational/educational purposes only.\nJuly 7, 2008 by Bill Sloman
(but blame the Q10 output stage on James Arthur).
TEXT -480 1176 Left 0 !.model BFR92A NPN(IS=0.1213E-15 VAF=30 BF=94.73
IKF=0.46227 XTB=0\n+BR=10.729 CJC=946.47E-15 CJE=10.416E-15
TR=1.2744E-9 TF=26.796E-12\n+ ITF=0.0044601 VTF=0.32861 XTF=0.3817
RB=14.998 RC=0.13793\n+RE=0.29088 Vceo=15 Icrating=4m mfg=Infineon)
TEXT 112 640 Left 0 ;Q2's collector is loaded by C2,\nlimiting
risetime. Q10 isolates\nQ1's collector, allowing that node\nto charge
much more rapidly.\n \nQ10 doubles as a common-base\namplifier stage,
further squaring up the\noutput from Q10's collector.\n \nThe new
output is taken from\nQ10's collector.\n \nJames Arthur, 9-Jul-2008

 

[Joerg]

James Arthur wrote:

How come that whenever I want to import netlists like the ones in this
thread into LTSpice I encounter an unknown syntax error? Upon "ignore"
the traces will be there but all the devices are missing.

 

[James Arthur]

James Arthur wrote:

How come that whenever I want to import netlists like the ones in this
thread into LTSpice I encounter an unknown syntax error? Upon "ignore"
the traces will be there but all the devices are missing.

Those errors are from line wraps. Make sure the last 3 "TEXT"
entries are each one-liners in your .asc file. That fixes it for me.

I modified one ouput and left one output virgin, for comparison.

HTH,
James Arthur

 

[Joerg]

Those errors are from line wraps. Make sure the last 3 "TEXT"
entries are each one-liners in your .asc file. That fixes it for me.

I modified one ouput and left one output virgin, for comparison.

Ah thanks, works now!

For fun I replaced Q1 and Q10 with BFP620. That makes for nice and
spiffy transitions, much more square and textbook style. Of course the
BFP620 is more expensive and like a hotrod on a sheet of ice.