Hans Summers wrote:

Hello

I have built 2 very simple 2-chip frequency counters with 8 LED binary
readout see http://www.hanssummers.com/radio/sfreq/index.htm . My Mk2
counter is extremely small (just 25 x 16 x 16mm) and consumes a low current
of 5mA max.

The question relates to the 4.096MHz oscillator which uses the internal
oscillator of the 74HC4060. Of the 5mA current consumption, 1.2mA is used by
the LED's when max 7 are on at any one time. About 0.8mA by the
diode-resistor gate logic, transistor switch, 74HC4040 and the voltage
regulator. Fully 3mA is wasted on the 74HC4060 crystal oscillator + divider.
It seems wrong to spend 60% of your current consumption on an oscillator,
compared to less than 25% on the LED's.

In the pursuit of excellence in this design, I would like to cut the current
consumption of the oscillator section. Does anyone know of a better
arrangement that will cut current consumption? Increasing the series
resistor wasn't the solution. I put a 100K variable in here in place of the
original 2K2. Initially as the resistor was increased the current
consumption fell, but at higher resistances the current consumption
increased quite dramatically. The optimum was at close to 4K7.

73 Hans G0UPL
http://www.HansSummers.com




Here's a suggestion. I've never tried this, so YMMV. You're using a
circuit that looks like:

|\ ___
.---| O-----|___|--.
| |/ R1 |
| |
| ___ |
o------|___|--------o
| R2 |
| _ |
| | | |
o-------|| ||-------o
| |_| |
| 4.096MHz |
--- C2 --- C1
--- ---
| |
| |
=== ===
GND GND
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Yes?

And you've maximized R2 and dinked with the value of R1, and the best
you can get is R1 = 4.7kOhm?

Probably what is happening is that you're fighting two contradictory
effects in the circuit: Effect one is that the inverter wants to have a
low-impedance output, so a low value of R1 will pull a lot of current
from the inverter output. Effect two is that a CMOS inverter is
designed assuming that it will be turned on hard; if it isn't then the
complementary pair of FETs just conduct current from the VSS rail to VDD.

I think that when you adjust R1 higher you're loading the output less,
but you're also supplying less voltage to the input. Your 4.7kOhm value
saves you output current, but drops the input voltage enough so that you
start seeing more input current.

Why don't you try playing with your feedback a little bit? I'm assuming
that you have C1 = C2. If you decrease C2 while increasing C1 so that
the series combination of C2 and C1 stays the same the voltage at the
inverter input should be stepped up. Depending on about a gazillion
factors this may reduce your current consumption.

I would try the circuit below:


|\ ___
.---| O-----|___|--.
| |/ R1 |
| |
| ___ |
o------|___|--------o
| R2 |
| _ |
| | | |
o-------|| ||-------o
| |_| |
| 4.096MHz |
--- C2 --- C1
--- ---
| |
o--------o Vtest |
| ===
--- C3 GND
---
|
|
===
GND
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Make sure R2 is as large as you can get away with and make C3 about ten
times bigger than the crystal's load capacitance, and leave C2 at about
the crystal's load capacitance. Now measure the voltage at Vtest
(please have an O-Scope!). Because you know C2 and C3 you can calculate
the voltage at the inverter input and keep it to 5Vp-p as you play with
C1 and R1.

Now play with C1 and R1 and see if you can (a) reduce power even more,
(b) keep a good strong signal at the inverter input and (c) keep your
desired frequency stability. Increasing C1 should give you more voltage
at C2, increasing R1 should give you less. There should be a point
where you get good performance at less current than you're getting now.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Tim Wescott wrote:
Hans Summers wrote:

Hello

I have built 2 very simple 2-chip frequency counters with 8 LED binary
readout see http://www.hanssummers.com/radio/sfreq/index.htm . My Mk2
counter is extremely small (just 25 x 16 x 16mm) and consumes a low
current
of 5mA max.

The question relates to the 4.096MHz oscillator which uses the internal
oscillator of the 74HC4060. Of the 5mA current consumption, 1.2mA is
used by
the LED's when max 7 are on at any one time. About 0.8mA by the
diode-resistor gate logic, transistor switch, 74HC4040 and the voltage
regulator. Fully 3mA is wasted on the 74HC4060 crystal oscillator +
divider.
It seems wrong to spend 60% of your current consumption on an oscillator,
compared to less than 25% on the LED's.

In the pursuit of excellence in this design, I would like to cut the
current
consumption of the oscillator section. Does anyone know of a better
arrangement that will cut current consumption? Increasing the series
resistor wasn't the solution. I put a 100K variable in here in place
of the
original 2K2. Initially as the resistor was increased the current
consumption fell, but at higher resistances the current consumption
increased quite dramatically. The optimum was at close to 4K7.

73 Hans G0UPL
http://www.HansSummers.com




Here's a suggestion. I've never tried this, so YMMV. You're using a
circuit that looks like:

|\ ___
.---| O-----|___|--.
| |/ R1 |
| |
| ___ |
o------|___|--------o
| R2 |
| _ |
| | | |
o-------|| ||-------o
| |_| |
| 4.096MHz |
--- C2 --- C1
--- ---
| |
| |
=== ===
GND GND
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Yes?

And you've maximized R2 and dinked with the value of R1, and the best
you can get is R1 = 4.7kOhm?

Probably what is happening is that you're fighting two contradictory
effects in the circuit: Effect one is that the inverter wants to have a
low-impedance output, so a low value of R1 will pull a lot of current
from the inverter output. Effect two is that a CMOS inverter is
designed assuming that it will be turned on hard; if it isn't then the
complementary pair of FETs just conduct current from the VSS rail to VDD.

I think that when you adjust R1 higher you're loading the output less,
but you're also supplying less voltage to the input. Your 4.7kOhm value
saves you output current, but drops the input voltage enough so that you
start seeing more input current.

Why don't you try playing with your feedback a little bit? I'm assuming
that you have C1 = C2. If you decrease C2 while increasing C1 so that
the series combination of C2 and C1 stays the same the voltage at the
inverter input should be stepped up. Depending on about a gazillion
factors this may reduce your current consumption.

I would try the circuit below:


|\ ___
.---| O-----|___|--.
| |/ R1 |
| |
| ___ |
o------|___|--------o
| R2 |
| _ |
| | | |
o-------|| ||-------o
| |_| |
| 4.096MHz |
--- C2 --- C1
--- ---
| |
o--------o Vtest |
| ===
--- C3 GND
---
|
|
===
GND
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Make sure R2 is as large as you can get away with and make C3 about ten
times bigger than the crystal's load capacitance, and leave C2 at about
the crystal's load capacitance. Now measure the voltage at Vtest
(please have an O-Scope!). Because you know C2 and C3 you can calculate
the voltage at the inverter input and keep it to 5Vp-p as you play with
C1 and R1.

Now play with C1 and R1 and see if you can (a) reduce power even more,
(b) keep a good strong signal at the inverter input and (c) keep your
desired frequency stability. Increasing C1 should give you more voltage
at C2, increasing R1 should give you less. There should be a point
where you get good performance at less current than you're getting now.


I just tried this with a 74HC04 (no HC4040s, no UHC04s more's the pity).
Best current draw was 1.6mA at 4MHz was with 4.7kOhm and C1 = C2 =
47pF. Then I stuck in a 455kHz ceramic resonator that I have lying
around and Bammo -- 750uA.

So maybe adjusting the frequency lower would be a good thing? Digi-Key
has 32kHz watch crystals.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Mon, 21 Jun 2004 16:31:08 +0000 (UTC), "Reg Edwards"
wrote:


The problems of how to get rid of relatively minute quantities of mildly
radioactive waste materials have been exaggerated by the oil conglomerates
and the other multi-national companies in the control of world governments.
They do it for obvious reasons via the international media which they also
own and control. Whoever owns and controls the Internet will ruthlessly
rule the Earth. Only the Chinese can prevent it.

God help us if the Chinese take over in 20 years' time.
But I was serious, Reg. There's nothing wrong with good ol' fashioned
fission. Just blast the leftover crap into space and have done with
it. It's lousy with radioactive debris anyway and the sun can swallow
everything we throw at it.
--

"What is now proved was once only imagin'd." - William Blake, 1793.

Hans Summers wrote:

Hello

I have built 2 very simple 2-chip frequency counters with 8 LED binary
readout see http://www.hanssummers.com/radio/sfreq/index.htm . My Mk2
counter is extremely small (just 25 x 16 x 16mm) and consumes a low current
of 5mA max.

The question relates to the 4.096MHz oscillator which uses the internal
oscillator of the 74HC4060. Of the 5mA current consumption, 1.2mA is used by
the LED's when max 7 are on at any one time. About 0.8mA by the
diode-resistor gate logic, transistor switch, 74HC4040 and the voltage
regulator. Fully 3mA is wasted on the 74HC4060 crystal oscillator + divider.
It seems wrong to spend 60% of your current consumption on an oscillator,
compared to less than 25% on the LED's.

In the pursuit of excellence in this design, I would like to cut the current
consumption of the oscillator section. Does anyone know of a better
arrangement that will cut current consumption? Increasing the series
resistor wasn't the solution. I put a 100K variable in here in place of the
original 2K2. Initially as the resistor was increased the current
consumption fell, but at higher resistances the current consumption
increased quite dramatically. The optimum was at close to 4K7.

73 Hans G0UPL
http://www.HansSummers.com



A 4060, using National's recommended circuit (from an '80 databook) and
a 32768Hz watch crystal, pulls 32 microamp -- and like I said before,
Digi-Key has 32000Hz crystals in stock, so there's your 1kHz reference.

Now if someone would explain why I bothered to prototype this...

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Mon, 21 Jun 2004 23:13:36 +0100, Paul Burridge
wrote:

God help us if the Chinese take over in 20 years' time.
But I was serious, Reg. There's nothing wrong with good ol' fashioned
fission. Just blast the leftover crap into space and have done with
it. It's lousy with radioactive debris anyway and the sun can swallow
everything we throw at it.

There are only two small problems with this approach, since first you
have to reach the 11.2 km/s escape velocity to escape the earth. The
Saturn V moon rocket was capable of delivering about 40 tons to escape
velocity.

With this velocity, you just end up in an orbit similar to the Earth's
orbit. In fact the Apollo 10 (or 12) third stage went into solar
orbit, but a year or two ago, it was captured by the Moon and Earth
and now it orbits the Earth for a year or two, before escaping back
into the solar orbit. With some bad luck, this stage might have hit
the Earth and imagine that it had contained 40 tons of highly
radioactive waste, which would spread into the atmosphere...

Thus, in order to avoid the risk of collisions with the earth in the
future, an additional rocket burn is required in the solar orbit to
prevent the orbit from intersecting with the orbit of the Earth. Thus
reducing the available payload.

If you want to drop something into the sun, you first must kill nearly
all of the 30 km/s orbital motion of the Earth. This would require a
huge amount of fuel and practically nothing would end up into the Sun.

It is in fact much easier to escape the solar system, since only about
43 km/s is required or 13 km/s in addition to the Earth's orbital
velocity. With Saturn V, maybe 500 kg would reach the solar escape
velocity directly.

Using Jupiter as a slingshot (as with Pioneer 11&12 and Voyager 1&2)
maybe a few tons could reach the solar escape velocity.

Unfortunately Saturn V does not exist any more and the Shuttle and the
Proton are toys compared to Saturn V. Any launch failure would also be
quite nasty with a lot of nuclear waste on board.

Paul OH3LWR

On Tue, 22 Jun 2004 10:19:41 +0300, Paul Keinanen
wrote:

If you want to drop something into the sun, you first must kill nearly
all of the 30 km/s orbital motion of the Earth. This would require a
huge amount of fuel and practically nothing would end up into the Sun.

Okay, well what about dumping it on the moon? Let's face it: there's
not a lot of other suitable uses for this redundant body - other than
providing tidal flows on Earth, of course. I guess you'd get some
complaints from these idiots who've 'bought plots of land' on the
moon, but they're never going to get to build on it in their lifetimes
so WGAS?
--

"What is now proved was once only imagin'd." - William Blake, 1793.

"Tim Wescott" wrote in message
...
Hans Summers wrote:

A 4060, using National's recommended circuit (from an '80 databook) and
a 32768Hz watch crystal, pulls 32 microamp -- and like I said before,
Digi-Key has 32000Hz crystals in stock, so there's your 1kHz reference.

Many thanks Tim. I didn't realise 32KHz crystals were available. The usual
32768 wouldn't give the right timing but 32KHz is perfect. You actually
prototyped this and measured the current? Did this use an old 4060 or a
74HC4060? What's the difference betweem families in terms of current
consumption? Also, how do these families compare to things like 74AC, 74ACT,
74HCT? I know the T means TTL-compatible levels rather than the old CMOS
family compatible levels, but is the current consumption different too?

What exact circuit is in your '80 databook? I just had a look at various
datasheets from different manufacturers, and all seem to have the same
configuration. The national datasheet for the 4060 shows values of 15M and
330K for the resistors to suit a watch crystal
http://cache.national.com/ds/CD/CD4020BC.pdf . I also found this 74HC4060
datasheet for the ON Semiconductor version. It includes an interesting
treatment of the calculation of the resistor values, see
http://www.farnell.com/datasheets/42247.pdf .

Loads of questions I know. But this is fantastic as it will enable me to
reduce the current consumption of the thing to under 1.5mA. I hope I'm right
in thinking that by replacing the LED switching transistor with a FET, I'll
also save some current consumption because of eliminating the base-emitter
current, but I'm not a FET expert.

Another nice thing is the 32KHz crystals are physically tiny: 6mm long and
2mm diameter. This means if I use SMD IC's I can make a next generation
counter a fraction the size of the current one which is already miniature.
One problem remains, which is getting hold of a 32KHz crystal. I have never
bought anything from Digikey. The part I need is XC972-ND and is priced (UK
pounds) £0.47. However I notice that there is a £10 handling fee and £12
shipping! The total order cost would be £22.47, for one simple crystal.
That's about US $41! Therefore does anyone in rec.radio.amateur.homebrew
reside in the US, order frequently or in the near future from Digikey, and
wouldn't mind adding one of those to their order and popping it in an
envelope to me - I'll pay all costs of course as long as you don't charge me
£10 handling ;-)

73 Hans G0UPL
http://www.HansSummers.com

Hans Summers wrote:

"Tim Wescott" wrote in message
...

Hans Summers wrote:

A 4060, using National's recommended circuit (from an '80 databook) and
a 32768Hz watch crystal, pulls 32 microamp -- and like I said before,
Digi-Key has 32000Hz crystals in stock, so there's your 1kHz reference.


Many thanks Tim. I didn't realise 32KHz crystals were available. The usual
32768 wouldn't give the right timing but 32KHz is perfect. You actually
prototyped this and measured the current? Did this use an old 4060 or a
74HC4060? What's the difference betweem families in terms of current
consumption? Also, how do these families compare to things like 74AC, 74ACT,
74HCT? I know the T means TTL-compatible levels rather than the old CMOS
family compatible levels, but is the current consumption different too?

Normally I resist the urge to prototype things, but yesterday was slow
and I could do this whole thing on a proto-board. I used a 4060, not a
74xCxxxx device. I have no idea how it'd play out on a xx4060, but with
a 74HC04 and the watch crystal I was seeing 1.6mA, and with the 4060 I
was seeing 32uA. This is an unfair test, because you're supposed to use
the 74HCU04 for oscillators; I have no idea how much this affected
things. I _did_ notice with the 74HC04 that running it at about 3V
brought the current down to the 30-50uA region, however.

What exact circuit is in your '80 databook? I just had a look at various
datasheets from different manufacturers, and all seem to have the same
configuration. The national datasheet for the 4060 shows values of 15M and
330K for the resistors to suit a watch crystal
http://cache.national.com/ds/CD/CD4020BC.pdf . I also found this 74HC4060
datasheet for the ON Semiconductor version. It includes an interesting
treatment of the calculation of the resistor values, see
http://www.farnell.com/datasheets/42247.pdf .

Your National datasheet matches the one in my databook.

Loads of questions I know. But this is fantastic as it will enable me to
reduce the current consumption of the thing to under 1.5mA. I hope I'm right
in thinking that by replacing the LED switching transistor with a FET, I'll
also save some current consumption because of eliminating the base-emitter
current, but I'm not a FET expert.

It should save a bit, but with a good junction transistor you should
only have to apply about 2-5% of the collector current to the base to
get saturation. If you're using one of the old standbys you should look
at newer transistors -- Zetex is good for this.

Another nice thing is the 32KHz crystals are physically tiny: 6mm long and
2mm diameter. This means if I use SMD IC's I can make a next generation
counter a fraction the size of the current one which is already miniature.
One problem remains, which is getting hold of a 32KHz crystal. I have never
bought anything from Digikey. The part I need is XC972-ND and is priced (UK
pounds) £0.47. However I notice that there is a £10 handling fee and £12
shipping! The total order cost would be £22.47, for one simple crystal.
That's about US $41! Therefore does anyone in rec.radio.amateur.homebrew
reside in the US, order frequently or in the near future from Digikey, and
wouldn't mind adding one of those to their order and popping it in an
envelope to me - I'll pay all costs of course as long as you don't charge me
£10 handling ;-)

The handling fee ($20 in the US) is only applied for small orders, so
you can either get $1.00 worth of stuff for $21, or you can get $21
worth of stuff for $21 -- this still doesn't save you the shipping
charges, though.

73 Hans G0UPL
http://www.HansSummers.com




--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

If this Mouser part will work, you won't have to deal with a minimum order.

http://www.mouser.com/index.cfm?hand..._pcodeid=69500

In case the link doesn't work, it's Mouser Part #: 695-CFV206-32K . 32
kHz, 12.5 pF.

73,


"PM"

Another nice thing is the 32KHz crystals are physically tiny: 6mm long and
2mm diameter. This means if I use SMD IC's I can make a next generation
counter a fraction the size of the current one which is already miniature.
One problem remains, which is getting hold of a 32KHz crystal. I have
never
bought anything from Digikey. The part I need is XC972-ND and is priced
(UK
pounds) £0.47. However I notice that there is a £10 handling fee and £12
shipping! The total order cost would be £22.47, for one simple crystal.
That's about US $41! Therefore does anyone in rec.radio.amateur.homebrew
reside in the US, order frequently or in the near future from Digikey, and
wouldn't mind adding one of those to their order and popping it in an
envelope to me - I'll pay all costs of course as long as you don't charge
me
£10 handling ;-)
========
Hans , May I suggest you check supply of above with Mode
Components -Birmingham, small company (no VAT)
www.modecomponents.co.uk

Frank GM0CSZ / KN6WH