Dodgy SSR ? Can't figure out what I have been doing wrong :-( Any ideas ? - Page 1
Forum section: electronics / beginners

author: simonboydfoley
author_rank: Contributor
timestamp: July 13, 2020, 12:46:49 am
content: Hi guysthis has had me stumped all weekend.I have built this fermentation controller that either drives a freezer to cool the beer or drives the heater in the freezer.I had a saint sien Arduino physical relay that worked OK until my Star's arrived. Now I have swapped out the relay for the SSR I can't get the AC current to the power sockets on the right.The DC trigger voltage works (3.4V) and I get a red light on the SSR, but the AC current won't flow. I only get 8mV on the terminal 1 to ground of the AC SSR and 0v on the terminal 2.FYI I have a AC to 12V DC Converter and feed that into a buck converter to drop to 5V DC so I can power àn option of 12v or 5v Arduino microcontrollers.Currently this is a Wemos D1 Mini being powered by 5v because it can't take 12V without frying.Any ideas ? I'm stumped.I bought a Pack of 3 X SSR's off Amazon for about 20 Euros so they are going to be fakes using a 20A Triac not a 40A. But even so it should still work. Unless these are incorrectly labeled DC switching SSR's and not AC?I have a spare SSR and I was going to test to see if I could light a lamp and increase the trigger voltage to see if 3.4 is not enough ...even though the LED does light.

author: eblc1388
author_rank: Frequent Contributor
timestamp: July 13, 2020, 12:55:44 am
content: Yes, do a simple test on the SSR with a lamp load only. It can pinpoint the problem immediately.However, if the SSR is not working, then one ac terminal should have the high voltage on it while the other has zero or very low voltage. This does not match with what you've described.

author: themadhippy
author_rank: Super Contributor
timestamp: July 13, 2020, 12:58:15 am
content: QuoteYou should have the full AC voltage on 1 terminal of the device,and often you'll also see something close to it on the on the other terminal even if the control side is off due to bleed through, so it seems the problem is on the AC side of things.Also try measuring to neutral instead of ground

author: simonboydfoley
author_rank: Contributor
timestamp: July 13, 2020, 06:48:12 am
content: I think it's a dodgy SSR as somebody else who bought the same SSR from Amazon also reported the same problem of the light going on but now switched current.Tonight I will do the lamp test and see what (if any) DC trigger voltage I can get an AC current to flow.Then I will take the unit apart and see what garbage Amazon has sold me. I'm sick and tired of getting fakes from Amazon Prime!I have ordered some replacement SSR's from a reputable company.Thx for your help ... I post the results

author: themadhippy
author_rank: Super Contributor
timestamp: July 13, 2020, 01:26:35 pm
content: Quotewhat are you calling ground as i dont see an electrical earth in the picture.

author: simonboydfoley
author_rank: Contributor
timestamp: July 13, 2020, 01:57:16 pm
content: Yes sorry I ment Neutral on the AC terminal not Ground.I'll check my Multimeter settings I thought it was auto sensing ... but I could have set it on the wrong settings

author: simonboydfoley
author_rank: Contributor
timestamp: July 13, 2020, 09:42:30 pm
content: Right first things first ... My Multimeter is not auto-sensing so when I changed mode to AC I did see 220v on terminal 1.When I tested the spare SSR with a lamp I found that the trigger voltage was 3.8v, where my wemos 5v 1A voltage rectifier was only delivering 3.4v on a 5.v supply.I guess I should wait for my new genuine SSR's to turn up as I can't trust this Amazon Prime fake.I suppose I could up the power supply on my wemos D1 mini to 6v and see if it can get to 4v on the output pins.I'm a bit wary as the D1 Mini is a clone and while the original can take 7-12v ....this Az Delivery clone burns out if you get near 12v.What do you recommend ?1.Wait for the genuine SSR to turn up and tare down this fake fotec and see how badly it's made and post back here ?Or2. Up the supply voltage on the D1 Mini ?🙄

author: simonboydfoley
author_rank: Contributor
timestamp: July 14, 2020, 08:02:49 pm
content: Well that was not a good idea :-(Tried increasing supply voltage on the D1 Mini Clone to 6v and kept getting I2C LCD Corruption.I stepped down the voltage 0.1v increments trying to find a voltage the LCD would work on ..... blown another D1 mini.Thast 5 units fried.I am sick of amazon selling dodgy crap, I can not find an orginal wemos D1 mini for love nor money to arrive at a reasonable time. :-(My real SSR's turn up tomorrow, i'll try my last AZ Delivery board and hopefully they will trigger from 3.4v on the PWM Pins.Its eiither that or im going to have to rig up a Transistor circuit driven by the PWM to trigger a 12v rail supply to the DC inputs on the SSR.This project has been a nightmare from start to finish!!!

author: bill_c
author_rank: Regular Contributor
timestamp: July 15, 2020, 01:46:34 am
content: Verify the SSR works properly before trying it with the D1 mini.Connect SSR 1 and 2 as a switch for a real AC load like the actual heater or a small AC motor, not that LED with who knows what kind of switching converter.Connect the power supply to 3 and 4. Increase DC voltage till SSR and heater turns on, record this voltage as Von.Decrease DC voltage till SSR turns off (easier to tell if using a motor), record this voltage as Voff.If this doesn't work then something is wrong with SSR or your test setup, no need to harm more D1 minis.If Von is less than 4 and Voff is more than 1.5 then connect SSR 3 to the 5V supply feeding the D1 mini and SSR 4 to the output on the D1 mini, drive output low to turn on SSR, Output hi or set as input to turn off SSR. This should give you about 4.4 volts to turn on SSR but may still have 1.something when you want it to turn off.If it fails to turn off properly then you will need a NPN transistor from DC ground to SSR 4 and a resistor from D1 mini to base of transistor, output hi to turn on, low to turn off, also add a pulldown resistor to mini output pin so it doesn't float if in some strange state.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: July 15, 2020, 08:37:13 am
content: Are you switching an inductive load? SSRs aren't so good at that. You said "freezer" so that sounds like a compressor.https://www.phidgets.com/docs/Solid_State_Relay_Primer#Identify_your_current

author: simonboydfoley
author_rank: Contributor
timestamp: July 15, 2020, 06:29:42 pm
content: Hi yes,the SSR's are used to trigger a freezer to cool fermenting beer or a space heater in the modified freezer to heat the bear up.However the Wemos D1 Mini Clone that I was using as the microcontroller could only generate 3.4v on the PWM pins that was acting as the DC trigger voltage.The crappy Fotec fake SSR's sold by Amazon was only triggering on 3.8v so it was lighting as switched ...but was in fact not switching the load AC at all!!!Now I have genuine SSR's installed it switches as low as 1.4v and is now working.What I don't know is why 5 of the Wemos D1 Mini clones keeps failing ! Admittedly some of them I powered with 12v because the originals could take it ... But the Az Delivery fakes are garbage and can not. However my last one failed 30min after flashing on 4.9v !!!!!I have ordered some original wemos dev board units to see if it's a bad batch from Az Delivery or if they have used substandard 5v 1A power converter chips and ripped everybody off.The only other thing I can think of is if my Buck converter that takes 12v down to 5v for the D1 Mini Clone is causing a voltage spike !While I had the crappy Fotec fake SRR's it looks like I blew my LCD display as I was upping the supply voltage to 6v to see of it would allow the PWM switching voltage to rise from 3.4 to 3.8v ....bad idea on my part!I have my last D1 Mini Clone working now with the new SSR's fine and it's working OK ... I bought it from a different company than Az Delivery so it could be half decent ....let's see how long it lasts.Personally I think that Amazon should be banned from selling electronic components or fined millions of $$$$ to get them to stop destroying the market with unsafe fake components ...Amazon are going to killl people with these Fotec Fakes ... The Triac on mine was 20A rated and they sold the unit as 40A !!!!I have had 1 month of hell with problems all caused by Amazon selling fake and dangerous products !!!!

author: simonboydfoley
author_rank: Contributor
timestamp: July 16, 2020, 05:44:06 am
content: Yup it's confirmed ....the problem with the failing D1 Mini Clones was fakes sold by Amazon from AZDelivery !!!!All 5 units supplied by AZDelivery failed and constantly failed to pick up the temperature oneWire readings.I put in a genuine Wemos D1 Mini and low and behold everything works and has been stable for 24hr .F****** Amazon selling dangerous fakes!Why should shops get punished for selling fake and shut down ....but Amazon gets away with undermining genuine by business's and ignoring all diligence for fakes and health and safety 😠😠😠😠😠😠😠

author: simonboydfoley
author_rank: Contributor
timestamp: July 18, 2020, 12:06:39 pm
content: Hi guysthanks for your help. With the new SSR the trigger voltage is 1.4v not 3.8v on the Fotek fakes.It turns out the PWM pins on the D1 Mini clone only to to 3.3v so it would never have worked on the dodgy SSR fakes.I have now found out why the D1 Mini clone where blowing .... I was following some idiots stupid documentation without checking it.1. I made a stupid stupid stupid decision to use 3.5mm stereo jacks to connect the DS18B20 temperature probes as per somebody docs.... because you need to use 2 pins for power and one pin for data on the OneWire sensoryou can short out thThiPWM pin if you connect the sensor when the unit is powered on.Even being careful not to do that ...any tension on the temperature probes cable can short the connector.2. And this is the real cause of the controller blowing (10 of them!!!!). ...the PWM pins are rated for 3.3v on these clones even though they provide a 5v rail. As per the docs I was pulling up the OneWire PWM data pin from the ***5v*** rail. This would work for a period of time but would eventually blow something in the ESP2866 controller chip data pin. It's voltage would then drop to 3.2v when high. The current draw would rise from 100mA to 250mV causing excess heat.Once I brought the OneWire PWM data pin high from the 3.3v rail ... The D1 Mini has stopped blowing.#TipsForYoungPlayers

author: robca
author_rank: Frequent Contributor
timestamp: July 19, 2020, 10:55:44 pm
content: Not sure what made you think that Wemos D1 can be used at 5V. All ESP8266 devices are strictly 3.3V devices, and no pin can provide more than 3.3V. So no Wemos D1 (clone or otherwise) will ever have a PWM above 3.3V. You can supply 5V to the proper pin of the D1 mini, because it has an onboard LDO that reduces that 5V to 3.3V, but everything else is 3.3VAlso, there is conflicting information on how 5V tolerant the ESP8266 actually is in input. In theory the input pins (not the power rail) can survive higher voltages, but in some cases, a 5V or above input voltage can result in a dead ESP8266 device. So my rule of thumb is to treat all ESP6266 devices as strictly 3.3V devices

author: simonboydfoley
author_rank: Contributor
timestamp: July 19, 2020, 11:06:03 pm
content: Agreed I made a mistake ... I was following somebody else documentation.. maybe other boards (eg the Arduino Uno) can take 5v on the PWM pins when bringing it high (giving the guys that did the fermentrack walkthrough a bit of leeway) ... But I got caught out because it *did* work for a while and I did follow the documentation ... It does fail eventually afterwards.

author: robca
author_rank: Frequent Contributor
timestamp: July 20, 2020, 03:44:57 pm
content: My post came out wrong, now that I re-read it. I didn't mean to "blame you", as much as clarify for you and any other people who might bump into this thread in the future that the Wemos D1 mini is a 3.3V device and that must be taken into account when interfacing with other devices. And that it's impossible to get anything more than 3.3V logic levels out of itOther Arduino compatible boards are 5V or, like the STM32 ones, 3.3V but have many pins that are 5V tolerant. It's always possible to use logic level translators to bump up 3.3V to 5V, if neededI'm glad you got your gremlins figured out