LC oscillator sensitivity analysis

On 06/03/2020 14:58, jlarkin@highlandsniptechnology.com wrote:

On Fri, 6 Mar 2020 08:40:13 -0000 (UTC), news@rblack01.plus.com wrote:

[snip]

I'm using 1210 surface-mount inductors from the likes of TDK, Murata,
Wurth. I think one of the Murata ones had a SPICE model but it didn't
include non-linearity or behaviour over temperature. The other vendors
just have bare data sheets with 'typical' values or impedance curves at
room temperature. Measuring the parts ended up being quicker than trying
to model them.


Did you get any tempcos? Most air-wound inductors have positive TCs in
the roughly +100 PPM/K range. But if the coil is stretched by the FR4
TCE, that has an effect too.

I'm about to learn some more about that.

[snip]
Sort of. We don't have an LCR meter, I should probably try to do
something about that.

What I did was test the various inductors on the PCB in an environmental
chamber, so what you get is the combined tempco of the L and the C,
which is more relevant to my application but possibly not as useful to
anyone else.
The last spin of the board used a TI FDC2212, which measures the
resonant frequency to an effective accuracy of about 250 Hz.

I'll dig out the numbers and post them on Monday if they're likely to be
of any use.

We did rent an LCR meter for another project years ago, big HP
boat-anchor of a thing, I forget the model number now. Something
similar would definitely help here.
<wanders off to eBay>

 

[John Larkin]

On Fri, 6 Mar 2020 22:14:18 +0000, news@rblack01.plus.com wrote:

On 06/03/2020 14:58, jlarkin@highlandsniptechnology.com wrote:
On Fri, 6 Mar 2020 08:40:13 -0000 (UTC), news@rblack01.plus.com wrote:

[snip]


I'm using 1210 surface-mount inductors from the likes of TDK, Murata,
Wurth. I think one of the Murata ones had a SPICE model but it didn't
include non-linearity or behaviour over temperature. The other vendors
just have bare data sheets with 'typical' values or impedance curves at
room temperature. Measuring the parts ended up being quicker than trying
to model them.


Did you get any tempcos? Most air-wound inductors have positive TCs in
the roughly +100 PPM/K range. But if the coil is stretched by the FR4
TCE, that has an effect too.

I'm about to learn some more about that.


[snip]
Sort of. We don't have an LCR meter, I should probably try to do
something about that.

What I did was test the various inductors on the PCB in an environmental
chamber, so what you get is the combined tempco of the L and the C,
which is more relevant to my application but possibly not as useful to
anyone else.
The last spin of the board used a TI FDC2212, which measures the
resonant frequency to an effective accuracy of about 250 Hz.

I'll dig out the numbers and post them on Monday if they're likely to be
of any use.

We did rent an LCR meter for another project years ago, big HP
boat-anchor of a thing, I forget the model number now. Something
similar would definitely help here.
wanders off to eBay

For PPM resolution, it's easier to build an oscillator and measure the
frequency. Use an NPO cap, and the inductor tempco will dominate.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Joe Gwinn]

On Fri, 6 Mar 2020 22:14:18 +0000, news@rblack01.plus.com wrote:

On 06/03/2020 14:58, jlarkin@highlandsniptechnology.com wrote:
On Fri, 6 Mar 2020 08:40:13 -0000 (UTC), news@rblack01.plus.com wrote:

[snip]


I'm using 1210 surface-mount inductors from the likes of TDK, Murata,
Wurth. I think one of the Murata ones had a SPICE model but it didn't
include non-linearity or behaviour over temperature. The other vendors
just have bare data sheets with 'typical' values or impedance curves at
room temperature. Measuring the parts ended up being quicker than trying
to model them.


Did you get any tempcos? Most air-wound inductors have positive TCs in
the roughly +100 PPM/K range. But if the coil is stretched by the FR4
TCE, that has an effect too.

I'm about to learn some more about that.


[snip]
Sort of. We don't have an LCR meter, I should probably try to do
something about that.

What I did was test the various inductors on the PCB in an environmental
chamber, so what you get is the combined tempco of the L and the C,
which is more relevant to my application but possibly not as useful to
anyone else.
The last spin of the board used a TI FDC2212, which measures the
resonant frequency to an effective accuracy of about 250 Hz.

I'll dig out the numbers and post them on Monday if they're likely to be
of any use.

We did rent an LCR meter for another project years ago, big HP
boat-anchor of a thing, I forget the model number now. Something
similar would definitely help here.
wanders off to eBay

There is a very good LCR meter from a Taiwanese source, that appears
to have been the real manufacturer of the prior generation of a
product from IET Labs, the inheritor of the General Radio line of
instruments. Der EE DE-5000 is the OEM version of the discontinued
IET Labs DE-5000. The IET Labs manual for the Der EE version is
identical. The design originated with GR. I personally own a
DE-5000, bought here:

..<https://www.ebay.com/p/20032261934>

Warning: Early models were vulnerable to mistakenly installing the
9-volt battery backwards.

Joe Gwinn

 

[John S]

On 3/8/2020 1:27 PM, Joe Gwinn wrote:

On Fri, 6 Mar 2020 22:14:18 +0000, news@rblack01.plus.com wrote:

On 06/03/2020 14:58, jlarkin@highlandsniptechnology.com wrote:
On Fri, 6 Mar 2020 08:40:13 -0000 (UTC), news@rblack01.plus.com wrote:

[snip]


I'm using 1210 surface-mount inductors from the likes of TDK, Murata,
Wurth. I think one of the Murata ones had a SPICE model but it didn't
include non-linearity or behaviour over temperature. The other vendors
just have bare data sheets with 'typical' values or impedance curves at
room temperature. Measuring the parts ended up being quicker than trying
to model them.


Did you get any tempcos? Most air-wound inductors have positive TCs in
the roughly +100 PPM/K range. But if the coil is stretched by the FR4
TCE, that has an effect too.

I'm about to learn some more about that.


[snip]
Sort of. We don't have an LCR meter, I should probably try to do
something about that.

What I did was test the various inductors on the PCB in an environmental
chamber, so what you get is the combined tempco of the L and the C,
which is more relevant to my application but possibly not as useful to
anyone else.
The last spin of the board used a TI FDC2212, which measures the
resonant frequency to an effective accuracy of about 250 Hz.

I'll dig out the numbers and post them on Monday if they're likely to be
of any use.

We did rent an LCR meter for another project years ago, big HP
boat-anchor of a thing, I forget the model number now. Something
similar would definitely help here.
wanders off to eBay

There is a very good LCR meter from a Taiwanese source, that appears
to have been the real manufacturer of the prior generation of a
product from IET Labs, the inheritor of the General Radio line of
instruments. Der EE DE-5000 is the OEM version of the discontinued
IET Labs DE-5000. The IET Labs manual for the Der EE version is
identical. The design originated with GR. I personally own a
DE-5000, bought here:

.<https://www.ebay.com/p/20032261934

Warning: Early models were vulnerable to mistakenly installing the
9-volt battery backwards.

Joe Gwinn

The manual looks great. The only thing it does not include is an
estimate of battery life. Do you have any info on that from your
personal experience?

The down side of this instrument is that 4 screws need to be removed to
replace the battery, but if the battery lasts for a long time (several
months) it might not be so bad.

Thanks, Joe.

 

Borrowed one of these once, from A&H, as their office is forty minutes from Campus. Also got a factory tour...

http://www.andeen-hagerling.com/ah2500a.htm

Steve

 

[John S]

On 3/14/2020 9:45 AM, sroberts6328@gmail.com wrote:

Borrowed one of these once, from A&H, as their office is forty minutes from Campus. Also got a factory tour...

http://www.andeen-hagerling.com/ah2500a.htm

Steve

Great! Send it to me. I'll pay the shipping charges.

 

[Joe Gwinn]

On Mon, 9 Mar 2020 07:37:51 -0500, John S <Sophi.2@invalid.org> wrote:

On 3/8/2020 1:27 PM, Joe Gwinn wrote:
On Fri, 6 Mar 2020 22:14:18 +0000, news@rblack01.plus.com wrote:

On 06/03/2020 14:58, jlarkin@highlandsniptechnology.com wrote:
On Fri, 6 Mar 2020 08:40:13 -0000 (UTC), news@rblack01.plus.com wrote:

[snip]


I'm using 1210 surface-mount inductors from the likes of TDK, Murata,
Wurth. I think one of the Murata ones had a SPICE model but it didn't
include non-linearity or behaviour over temperature. The other vendors
just have bare data sheets with 'typical' values or impedance curves at
room temperature. Measuring the parts ended up being quicker than trying
to model them.


Did you get any tempcos? Most air-wound inductors have positive TCs in
the roughly +100 PPM/K range. But if the coil is stretched by the FR4
TCE, that has an effect too.

I'm about to learn some more about that.


[snip]
Sort of. We don't have an LCR meter, I should probably try to do
something about that.

What I did was test the various inductors on the PCB in an environmental
chamber, so what you get is the combined tempco of the L and the C,
which is more relevant to my application but possibly not as useful to
anyone else.
The last spin of the board used a TI FDC2212, which measures the
resonant frequency to an effective accuracy of about 250 Hz.

I'll dig out the numbers and post them on Monday if they're likely to be
of any use.

We did rent an LCR meter for another project years ago, big HP
boat-anchor of a thing, I forget the model number now. Something
similar would definitely help here.
wanders off to eBay

There is a very good LCR meter from a Taiwanese source, that appears
to have been the real manufacturer of the prior generation of a
product from IET Labs, the inheritor of the General Radio line of
instruments. Der EE DE-5000 is the OEM version of the discontinued
IET Labs DE-5000. The IET Labs manual for the Der EE version is
identical. The design originated with GR. I personally own a
DE-5000, bought here:

.<https://www.ebay.com/p/20032261934

Warning: Early models were vulnerable to mistakenly installing the
9-volt battery backwards.

Joe Gwinn


The manual looks great. The only thing it does not include is an
estimate of battery life. Do you have any info on that from your
personal experience?

The down side of this instrument is that 4 screws need to be removed to
replace the battery, but if the battery lasts for a long time (several
months) it might not be so bad.

Thanks, Joe.

Welcome.

I don't know the battery life, but I have not yet had to replace it.

Replacing the battery is pretty fast.

Joe Gwinn