INA122PA Replacement - Page 1
Forum section: electronics / beginners

author: mistr3x
author_rank: Newbie
timestamp: June 22, 2023, 01:40:04 pm
content: Hi, im new in this and i need help with something, i dont know nothing at all of electronic but i need something to replace tis little fella hereim trying to replicate a simracing brake load cell pedal but in my country such component doesnt exist and importing is such a pain in argentina, so i want some help in what component could i get in replacement of this one it needs to have a quick update response as is for gaming applications.Hereis the back of the board if neededThis is where i got the idea fromThanks in advance

author: Vovk_Z
author_rank: Super Contributor
timestamp: June 22, 2023, 01:41:37 pm
content: I'm not sure there is a replacement for any INAxxx IC.

author: mistr3x
author_rank: Newbie
timestamp: June 22, 2023, 01:48:50 pm
content: Is it possible to recreate the entire circuit, then?

author: Vovk_Z
author_rank: Super Contributor
timestamp: June 22, 2023, 02:03:12 pm
content: Yes, to some degree of accuracy. Datasheet in help.INA122 datasheetYou may start with OP07 as an opamp.I would recommend beginning with a Great Book 'The Art Of Electronics' by Horowitz and Hill. There is a chapter about opamps in general and precision instrumentation circuits like that.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 23, 2023, 09:06:50 am
content: Dont these pedals connect via usb? So there is some processor converting the load cell voltage to digital. Use a load cell amp with digital output.The HX711 a load cell amp can be found under any stone. It will cost a lot less than a regular instamp ic and it talk to your arduino or what ever without the need for any additional electronics.https://listado.mercadolibre.com.ar/hx711Mientras tanto...You can buy INA122P direct from Texas Instruments $6.60 each.Mostly vendors offer it in an smaller ic package (SO-8) eg listado.mercadolibre.com.ar/ina122#D[A:ina122]Use an adaptor if you really need the bigger IC version.https://articulo.mercadolibre.com.ar/MLA-1112875855-adaptador-smd-soic8ssop8-a-dip8-x-10-unidades-_JM#position=31&search_layout=grid&type=item&tracking_id=955d389d-cefe-4b86-b927-113cac5428e7Is this the thing in the photo what you need or will something doing the same job be acceptable?Many other inst amps will perform the same function. It will be easy to find a similar amp. The INA122 can be used on a single supply. Taking the amp type and INA122 specifics, you might replace it with an AD8227 for example. On eBay I saw INA333, AD623, AD620 and AD8221AR modules all of which can be used as a load-cell amps. My guess is the schematic attached is your pcb- mind reading set to max.On Aliexpress I saw this load cell amplifier. Search for "Instrument Precision Amplifier / MV Millivolt Differential Amplifier / Voltage Amplifier Module / Sensor Amplifier" That grey pcb (see photo) is just the job. You need to work know what maximum gain you need when ordering. Then, they are so cheap. Just buy one of each and try them out. Fine tuning can be applied to its output if you need.

author: mistr3x
author_rank: Newbie
timestamp: June 23, 2023, 04:05:08 pm
content: Thanks a lot about everything!problem w/ imports here is cant bring no more than 3 per import so i will need to figure something outAgain thank you for your time and explaining!

author: Terry Bites
author_rank: Super Contributor
timestamp: June 23, 2023, 06:00:29 pm
content: How many load cells will you be using, more than 3I could lay out a very basic pcb that you could have made by pcbway or similar. Then you can solder the parts in.Mail me via the back channel.If its a one off I'll do it for free.

author: mistr3x
author_rank: Newbie
timestamp: June 25, 2023, 04:53:55 am
content: I will be using just one, for the brakes, the gas and clutch will be hall sensorsthe pcb that i showed off in the pics on the post doesnt need arduino, i can directly connect them to the pedal original wiring and it will work fine

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 25, 2023, 07:09:05 am
content: Are there any marketplace like Aliexpress or similar local equivalent in your country? Strain gauge/load cell amplifier are used commonly enough that there almost certain supply of already made modules on such marketplace.

author: mistr3x
author_rank: Newbie
timestamp: June 26, 2023, 11:15:24 am
content: Quote from: ArdWar on June 25, 2023, 07:09:05 amSadly nope, and as i said before it coste like 60U$D just the shipping of the chipthe closest thing of a load cell amplifier here in ar is a HX711 but since that needs arduino to run doesnt fit my needs

author: Terry Bites
author_rank: Super Contributor
timestamp: June 27, 2023, 12:23:28 pm
content: nah..... too much google laziness here..... log in to TI, you have to buy a tube of 10. $66My account (create your own, its allowed) it shows over 600 in stock. They'll ship worldwide.BTW, dug up an old 4 channel single/ dual supply through hole PCB from my archives, you want my gerbers?

author: wraper
author_rank: Unknown
timestamp: June 27, 2023, 12:51:30 pm
content: INA122 is a far from the best to be used like this, especially for the price. Not only it is expensive, it has quite a bit of offset and offset temperature drift. You want auto-zero instrumentation amplifier. INA188 makes way more sense for example. For load cell applications like yours I personally use much cheaper AD8293G160 which has a fixed gain of 160. Although due to fine pin pitch it's not that easy to solder without skill. If you are going to use pedals together with a force feedback steering wheel, you need to be aware that many of those produce hell a lot noise due to PWMing a high power brushless motor. If there is no proper in-amp input filtering, it may drive your circuit totally nuts.

author: Eraldo
author_rank: Regular Contributor
timestamp: June 27, 2023, 01:01:06 pm
content: As some said i would just try to build it myself with a dual opamp ic chip and a few external resistors like in the diagram of the ina122. The potentiometer is 1k ohm and is just used as an external variable resistor (you connect the center tap with one of the other legs of the pot) also the specs of the opamp you use such as voltage and current offset don't seem critical in this application and a generic lm358 could do the job for testing.

author: wraper
author_rank: Unknown
timestamp: June 27, 2023, 02:10:03 pm
content: Quote from: Eraldo on June 27, 2023, 01:01:06 pmDo not suggest that. Input offset voltage can be higher than full scale of a load cell. For example if you use 1mV/V load cell powered from 5V its full scale is just 5mV.

author: magic
author_rank: Super Contributor
timestamp: June 27, 2023, 02:29:30 pm
content: To be fair, this is not a precision measurement application and it's completely unclear what the requirements are.

author: mistr3x
author_rank: Newbie
timestamp: June 27, 2023, 05:10:35 pm
content: Quote from: Terry Bites on June 27, 2023, 12:23:28 pmit seems you dont know import laws pretty well, so let me get to you in that matter:No more than 3 products (of thesame type)are allowed per shipping.The Product itself cannot be over 1000-3000U$D (shipping cost included)Maximum imports per year 12 (1 per month)Max Package weight 50kgsSo yeah i know what im talking about and i said 60U$D bc of 30 being shipping to usa and + 30U$D being from us a to argentina (if i import directly from china customs just retains the package indefinetly unless you are an certified importer) so yeah i think i know what im talking about when i say I CANT GET THAT INTO MY COUNTRY WITHOUT PAYING CRAZY PRICEShttps://www.afip.gob.ar/envios-internacionales/puerta-a-puerta/procedimiento.asphttps://epago.correoargentino.com.ar/#/loginTAXES IN ARG:30% per payment in dollars by AFIP.35% per payment in retentions by AFIP.15% tax by AFIP50% tax if shipped product goes above 50U$D20% tax National Postal Handling concept.TOTAL = 150% tax for 3 chips

author: mistr3x
author_rank: Newbie
timestamp: June 27, 2023, 05:30:25 pm
content: Quote from: wraper on June 27, 2023, 12:51:30 pmi use the pedals apart from the steering wheelwith a 10bit conversion box

author: wraper
author_rank: Unknown
timestamp: June 27, 2023, 05:38:45 pm
content: Quote from: mistr3x on June 27, 2023, 05:30:25 pmIt does not need to be the same device. If force feedback steering wheel is connected to the same computer or even worse, mounted on the same metal chassis, it's enough to cause total havoc in pedal load cell amplifiers. How do I know it? Because I was contracted to fix the problem in sim pedals which were sold in many thousands of units. It probably will be fine if wheel is a cheap Thrustmaster garbage though.