Weller WE1010 conversion for WSP80 handle  - Page 1
Forum section: electronics / repair

author: badyl00
author_rank: Contributor
timestamp: February 25, 2021, 11:29:23 am
content: Hello. Looking for help with conversion WE1010 station to work with WSP80 handle. Originally it works with WEP70 handle. It have different temp sensor inside. I added original schematic from board. Next i disconnected op amp output from uC and add 0-5V power supply. Then I measured changes voltage on uC input to temperature on LCD display. Not sure about op amp type. It have marking YG69 but in weller works similar MCP types. On next image i drawn schematic from WSD81 originally working with WSP80. Maybe someone can calculate how to change values near op amp to get work WE1010 with WSP80 handle ?

author: wraper
author_rank: Unknown
timestamp: February 25, 2021, 11:43:44 am
content: What different sensor? Did you make any measurements of sensor? Circuit looks like it uses thermocouple. If other type uses resistive sensor, there is no simple conversion. EDIT: did not notice there was a second circuit. Yeah it looks like one uses thermocouple but other uses resistive sensor.

author: badyl00
author_rank: Contributor
timestamp: February 25, 2021, 11:47:00 am
content: Only found this:https://www.old.telec16.fr/content/electronique/fer/fer.htmlThink both types are PTC. I don't have WEP70 to take measures.

author: wraper
author_rank: Unknown
timestamp: February 25, 2021, 11:49:35 am
content: Quote from: badyl00 on February 25, 2021, 11:47:00 amIt says WEP70 uses thermocouple.

author: wraper
author_rank: Unknown
timestamp: February 25, 2021, 11:53:45 am
content: IMHO the only option to not make it overcomplicated and working decently is adding proper amplifier for sensor type and MCU. Which will then read the voltage from it's ADC, calculate conversion and output PWM which is then smoothed and used instead of output from original sensor amplifier.

author: badyl00
author_rank: Contributor
timestamp: February 25, 2021, 12:03:58 pm
content: Quote from: wraper on February 25, 2021, 11:49:35 amIt says temperature sensor is unknown. Think changes of resistors can solve problem but don't know how to calculate values. PCB is prepared to changes because have not mounted resistors.Oryginal looks like this:

author: wraper
author_rank: Unknown
timestamp: February 25, 2021, 12:08:01 pm
content: it says thermocouple type with question mark which, as I understand, means unknown thermocouple type and 3 Ohm. 3 ohm is basically impossible for resistive sensor. Nor schematic could possibly work with resistive sensor.

author: badyl00
author_rank: Contributor
timestamp: February 25, 2021, 12:18:24 pm
content: Think 3 ohms is wrong measure. I can add a variable resistor on input of station and take characteristic of Rin/Temp on display.

author: wraper
author_rank: Unknown
timestamp: February 25, 2021, 12:20:56 pm
content: Why would it be wrong? It's a completely reasonable resistance for thermocouple. Do you understand what thermocouple is?

author: badyl00
author_rank: Contributor
timestamp: February 25, 2021, 12:35:23 pm
content: Quote from: wraper on February 25, 2021, 12:20:56 pmYes understand.

author: wraper
author_rank: Unknown
timestamp: February 25, 2021, 12:40:09 pm
content: So, to make it work in purely analog way, you need to somehow linearize output voltage, as it's not linear at all. To make it basically linear as with thermocouple. And if possible replace built in temperature sensor with fixed resistor. Still accuracy over the range will not be very good.

author: badyl00
author_rank: Contributor
timestamp: February 25, 2021, 01:56:36 pm
content: Quote from: wraper on February 25, 2021, 12:40:09 pmBut in WEP70 opamp output voltage is linear to temp and for WSP80 same. So it's not possible to change starting point of characteristic and slope of output V/Temp ? Maybe I thinking wrong.

author: wraper
author_rank: Unknown
timestamp: February 25, 2021, 02:10:59 pm
content: Quote from: badyl00 on February 25, 2021, 01:56:36 pmDid you actually measure it?

author: badyl00
author_rank: Contributor
timestamp: February 25, 2021, 02:19:43 pm
content: For WSP80 characteristic is on internet and for WEP70 I wrote values in table. Looks linear. Op amp in both schematics works in linear mode i think.https://www.edaboard.com/threads/schematics-from-weller-pu81-power-unit-for-wsp80.90461/

author: wraper
author_rank: Unknown
timestamp: February 25, 2021, 02:46:01 pm
content: If it's really linear, this should be fairly precise if I did no mistakes with calculations and figures on internet were correct (assuming your measurements were done at 20oC ambient temperature). To make it not drift because of ambient temperature change, you should find temperature sensor on PCB. If it's a thermistor, then measure it's resistance at room temperature and replace with fixed resistor. EDIT: for some dumb reason I assumed your temperature/voltage table was in Fahrenheit. So deleted schematic and will recalculate the values.

author: badyl00
author_rank: Contributor
timestamp: February 25, 2021, 07:19:31 pm
content: Sorry. All temperatures are in celsius. Schematic opamp_we1010 need to be changed . Schematic Wsd81 I only attached to look how its build to work with wsp80 handle in other station.

author: wraper
author_rank: Unknown
timestamp: February 25, 2021, 07:41:40 pm
content: Quote from: badyl00 on February 25, 2021, 07:19:31 pmYou need to modify WE1010 amplifier to be the same as WSD81, just with different resistor values. There is no way to keep it as is and use fundamentally different type of sensor.

author: badyl00
author_rank: Contributor
timestamp: February 25, 2021, 08:44:20 pm
content: Can you add equations to you calculations ?

author: wraper
author_rank: Unknown
timestamp: February 25, 2021, 08:59:40 pm
content: Sensor Resistance Rsens = 19.96*0.113*temp. Input voltage Vin = 5V * Rsens/(Rsens + R1). Output voltage Vout = (Vin-Voffset)*Gain. Voffset = 0.0723V, divided by R2, R3 to get approximately the same voltage as Vin at 22oC, Gain = 17.6. For R4 calculation to get required opamp gain, it can be approximated that R6 is connected to GND since R2, R3 divider has negligible output resistance.

author: antek133
author_rank: Newbie
timestamp: March 17, 2023, 07:02:30 am
content: Witam. Czy poruszony temat został rozwiązany, czy wszystko działa poprawnie ?

author: mb.raghavendra@gmail.com
author_rank: Newbie
timestamp: November 28, 2023, 05:31:04 pm
content: Hi All,Looking for help with conversion of WSD81 station to work with WEP70 handle(Iron). . . I have added schematic for WSD81, Temp to ohm measurement of WEP70 .Can someone calculate how to change values near op amp to get work WSD81 with WEP70 handle?Also observed that WEP70 sensor output is 42uv per deg C. Connected MAX31856 Thermocouple to Digital Converter as K type and there is difference up to 30 deg C. If used as J type, 10 deg C difference . i want use existing circuit ofWSD81 with amplifier modification.I disconnected op amp output from uC(PIC 16F833) and added 0-5V power supply. Then I measured changes voltage on uC input to temperature on display.3.46V -> 450C3.6V -> 430C3.5V -> 420C3.08V -> 350C2.76V -> 300C2.41V -> 250C2.06V -> 200C1.72V -> 150C1.55 -> 125C1.31 -> 100CTemp vs Ohm for WEP70https://drive.google.com/file/d/1rnwCHuXmn1hN-6EV6Uaop-YM5JTENz22/view?usp=sharingWSD81 Schematichttps://drive.google.com/file/d/13FuGd4SxCQ4SbISW1Xo0eS6DBc5uD1Re/view?usp=sharing