LF357 substitute

[algan]

I have tested the TLE2081ACP and it is not a replacement for the LF357. I don't think they are much different from the TLE2071CP, but if any colleague tests it, please write how it works.

[Detectorist#1]

Hi algan,
Which exact parameter of TLE2081ACP not allows the replacement of LF357 in Delta Pulse MD?

[Maurizio2]

And you tested the LT1122 on some pulse metal detector like Delta Pulse2 or Polonaise Pi, tell me if it definitely works compared to the fake ones, is there a drastic difference in depth. It is not said that if the parameters are good, it will work.

I used it in the past to replace LF357 in a pulse metal detector called Minipulse III.
It works fine.

[Maurizio2]

The real substitution of LF357 for Delta Pulse MD is TLE2071CP with guaranteed work at input voltage equivalent to Vcc and with price of only 1.60Euro. Other parameters are 9.4MHz bandwidth and 35V/us slew rate.

The TLE2071 is a direct replacement, but only if used for filters.
Here, the most important parameters are the slew rate and the settling time, for example.
The LT1122 is also very precise, which is why it costs much more, but it is the ideal candidate for this application.
The only problem is that it's expensive.

[algan]

Okay, when I make my next orders, I will order and test the LT1122 to see if it works like the original LF357 with the pi polonaise board, I know what coin catches the original with the 28cm antenna.
Colleague, Detectorist#1 I have tested other ICs similar to the TLE2071 rail to rail and I have noticed that such ICs are not suitable for work, they work, but the detector has no depth.

[GeoMax]

I used it in the past to replace LF357 in a pulse metal detector called Minipulse III.
It works fine.

"Minipulse III" what kind of detector is this? Never hear about this. Any further informations or schematic available?

[Maurizio2]

"Minipulse III" what kind of detector is this? Never hear about this. Any further informations or schematic available?

The website for this detector has been shut down and was originally German, the website was in English though.
However, you can find it on Google by typing the following keywords: minipuls 3 schematic.

It uses an Atmel AT90S4433 microcontroller, and I've previously modified the code to work with an ATmega8 (which is easy to find).

[GeoMax]

Hi Maurizio2,

thanks for the info. Yes, I remember this detector from 2002. I was a bit confused because of the number style "III". I know it only as "Minipulse 3".

[Maurizio2]

Hi Maurizio2,

thanks for the info. Yes, I remember this detector from 2002. I was a bit confused because of the number style "III". I know it only as "Minipulse 3".

III is 3 in Roman numerals.
It is very common in Europe.

[Detectorist#1]

Hi Maurizio2,
Now, we talk for the possibility of the replacement of LF357 in the first stage of Delta Pulse MD. For your information, if you read carefully the datasheets, the slew rate of TLE2071 is 35V/us and setting time is 1.5us when the power voltages are +/-5V. The slew rate of LF357 is 50V/us and the setting time is also 1.5us. Please, find other arguments.
For using of LT1122, you are in deep mistake - read please again the page 3 of the datasheet - input voltage range is Vss+4V to Vcc-4V typical - this totally eliminate the possibility to use this OpAmp in the first stage of Delta Pulse MD! I repeat again and again - in Delta Pulse MD input voltages of first RX stage are equal to Vcc!!!!!!

[Detectorist#1]

Hi algan,
If you not know why some OpAmp not works well, it is sure - you don't know why some OpAmp works well.

[Maurizio2]

Hi Maurizio2,
Now, we talk for the possibility of the replacement of LF357 in the first stage of Delta Pulse MD. For your information, if you read carefully the datasheets, the slew rate of TLE2071 is 35V/us and setting time is 1.5us when the power voltages are +/-5V. The slew rate of LF357 is 50V/us and the setting time is also 1.5us. Please, find other arguments.
For using of LT1122, you are in deep mistake - read please again the page 3 of the datasheet - input voltage range is Vss+4V to Vcc-4V typical - this totally eliminate the possibility to use this OpAmp in the first stage of Delta Pulse MD! I repeat again and again - in Delta Pulse MD input voltages of first RX stage are equal to Vcc!!!!!!

Hi Detectorist#1,
however, as you are telling, the slew rate of TLE2071 is lower if compared to LF357.

You are right, I hadn't seen the Delta Pulse schematic diagram. Please, give me the time to search an alternative good with this detector, thank you.

[Maurizio2]

Hi,
I was looking at the OPA637 (very expensive), but it has the same problem as the LT1122, so it's not suitable for the Delta Pulse.
But in other cases, it can replace the LF357 just as well as the LT1122.

Then I moved on to the OPA992, but its specifications are similar to the TLE2071, except for the package.

Finally, I looked at the AD8033, which, with a +-12V supply, has an input voltage range of −12.0 to +9.0V.

Sorry but for Delta Pulse lovers it is better to look for a "New Old Stock" LF357 or fall back on the TLE2071.

[Qiaozhi]

"Minipulse III" what kind of detector is this? Never hear about this. Any further informations or schematic available?

This appears to be it ->
https://simplemetaldetector.com/puls...?cn-reloaded=1
It called the Minipuls-3. Note the spelling.

Not to be confused with the Pulse Technology Minipulse, or Geotech's Minipulse Plus.

[GeoMax]

Hello Qiaozhi,

I know that "pulse" in English is "Puls" in German... Sometimes I mix up the two languages.