Schematic for SparkFun Load Cell Amplifier

Terminal
An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
natarius
Ground
A common return path for electric current. Commonly known as ground.
jharwinbarrozo
20.5M
Net Portal
A net identifier used to create connectivity to other Net Portal with the same designator. #portal
jharwinbarrozo
43.0M
Power Net Portal
Power net portal is a special schematic object used to define a power or ground net. Power ports allow you to conveniently indicate a power net at any location in the design. Power nets of the same designator automatically connect throughout your design #portal #power
jharwinbarrozo
11.4M
Generic Resistor
A generic fixed resistor for rapid developing circuit topology. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0Ω 10Ω 100Ω 1.0kΩ 10kΩ 100kΩ 1.0MΩ 1.1Ω 11Ω 110Ω 1.1kΩ 11kΩ 110kΩ 1.1MΩ 1.2Ω 12Ω 120Ω 1.2kΩ 12kΩ 120kΩ 1.2MΩ 1.3Ω 13Ω 130Ω 1.3kΩ 13kΩ 130kΩ 1.3MΩ 1.5Ω 15Ω 150Ω 1.5kΩ 15kΩ 150kΩ 1.5MΩ 1.6Ω 16Ω 160Ω 1.6kΩ 16kΩ 160kΩ 1.6MΩ 1.8Ω 18Ω 180Ω 1.8KΩ 18kΩ 180kΩ 1.8MΩ 2.0Ω 20Ω 200Ω 2.0kΩ 20kΩ 200kΩ 2.0MΩ 2.2Ω 22Ω 220Ω 2.2kΩ 22kΩ 220kΩ 2.2MΩ 2.4Ω 24Ω 240Ω 2.4kΩ 24kΩ 240kΩ 2.4MΩ 2.7Ω 27Ω 270Ω 2.7kΩ 27kΩ 270kΩ 2.7MΩ 3.0Ω 30Ω 300Ω 3.0KΩ 30KΩ 300KΩ 3.0MΩ 3.3Ω 33Ω 330Ω 3.3kΩ 33kΩ 330kΩ 3.3MΩ 3.6Ω 36Ω 360Ω 3.6kΩ 36kΩ 360kΩ 3.6MΩ 3.9Ω 39Ω 390Ω 3.9kΩ 39kΩ 390kΩ 3.9MΩ 4.3Ω 43Ω 430Ω 4.3kΩ 43KΩ 430KΩ 4.3MΩ 4.7Ω 47Ω 470Ω 4.7kΩ 47kΩ 470kΩ 4.7MΩ 5.1Ω 51Ω 510Ω 5.1kΩ 51kΩ 510kΩ 5.1MΩ 5.6Ω 56Ω 560Ω 5.6kΩ 56kΩ 560kΩ 5.6MΩ 6.2Ω 62Ω 620Ω 6.2kΩ 62KΩ 620KΩ 6.2MΩ 6.8Ω 68Ω 680Ω 6.8kΩ 68kΩ 680kΩ 6.8MΩ 7.5Ω 75Ω 750Ω 7.5kΩ 75kΩ 750kΩ 7.5MΩ 8.2Ω 82Ω 820Ω 8.2kΩ 82kΩ 820kΩ 8.2MΩ 9.1Ω 91Ω 910Ω 9.1kΩ 91kΩ 910kΩ 9.1MΩ #generics #CommonPartsLibrary
jharwinbarrozo
1.5M
Generic Capacitor
A generic fixed capacitor for rapid developing circuit topology. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF 10pF 100pF 1000pF 0.01uF 0.1uF 1.0uF 10uF 100uF 1000uF 10,000uF 1.1pF 11pF 110pF 1100pF 1.2pF 12pF 120pF 1200pF 1.3pF 13pF 130pF 1300pF 1.5pF 15pF 150pF 1500pF 0.015uF 0.15uF 1.5uF 15uF 150uF 1500uF 1.6pF 16pF 160pF 1600pF 1.8pF 18pF 180pF 1800pF 2.0pF 20pF 200pF 2000pF 2.2pF 22pF 20pF 2200pF 0.022uF 0.22uF 2.2uF 22uF 220uF 2200uF 2.4pF 24pF 240pF 2400pF 2.7pF 27pF 270pF 2700pF 3.0pF 30pF 300pF 3000pF 3.3pF 33pF 330pF 3300pF 0.033uF 0.33uF 3.3uF 33uF 330uF 3300uF 3.6pF 36pF 360pF 3600pF 3.9pF 39pF 390pF 3900pF 4.3pF 43pF 430pF 4300pF 4.7pF 47pF 470pF 4700pF 0.047uF 0.47uF 4.7uF 47uF 470uF 4700uF 5.1pF 51pF 510pF 5100pF 5.6pF 56pF 560pF 5600pF 6.2pF 62pF 620pF 6200pF 6.8pF 68pF 680pF 6800pF 0.068uF 0.68uF 6.8uF 68uF 680uF 6800uF 7.5pF 75pF 750pF 7500pF 8.2pF 82pF 820pF 8200pF 9.1pF 91pF 910pF 9100pF #generics #CommonPartsLibrary
jharwinbarrozo
1.5M
Generic Inductor
A generic fixed inductor for rapid developing circuit topology. *You can now change the footprint and 3D model at the top level anytime you want. This is the power of #generics
jharwinbarrozo
14.4k
RMCF0805JT47K0
47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film #forLedBlink
jharwinbarrozo
1.2M
875105359001
10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcan
jharwinbarrozo
1.2M
CTL1206FYW1T
Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlink
jharwinbarrozo
1.1M

please explain what Q1 does.

@copilot please explain what Q1 does.

The component Q1 is a transistor with the manufacturer's part number MMBT4403. Transistors, like the one in this schematic, are versatile devices used for signal amplification, switching, voltage regulation, signal modulation, and many other functions.

This transistor is in a PNP configuration. PNP transistors work in a way that when there's no voltage difference between the base (B) and emitter (E), the transistor is "on" and current can flow from the collector (C) to the emitter (E), effectively working as a current source. When the voltage at the base (B) is pulled low, the current flow from the collector (C) to the emitter (E) is "off", or stopped.

Now, for the exact role of Q1 in this circuit, we need more information about how the pins are connected. However, given what we have, the PNP transistor might be used here for a variety of functions, such as acting as a switch, an amplifier, or part of a power regulation stage. Some more typical roles for a PNP transistor like this could include:

Switch: If the transistor is controlling power to a part of the circuit. In this case, changing the base-emitter voltage would effectively switch power on or off to that part of the circuit.
Amplifier: If this circuit is dealing with analog signals, it could be part of an amplifier stage—perhaps for the load cell signal.
Power regulation: If this circuit needs a stable voltage source, the transistor could be part of a regulator stage.

Without more specifics about the connections and overall goal of your circuit, it's hard to say the exact role of the transistor. Nonetheless, its general function would be along the lines of controlling current flow based on the input at the base pin (B).

Someone is typing...

SCK

Resistance

20k Ω

A+

Resistance

100 Ω

Capacitance

10u F

VDD

A-

Resistance

8.2k Ω

VCC

Capacitance

0.1u F

Resistance

10k Ω

DAT

Resistance

100 Ω

Capacitance

0.1u F

VCC

JP1

SCK

Capacitance

10u F

Capacitance

0.1u F

A+

DAT

VDD

VCC

Capacitance

0.1u F

VDD

VCC

Inductance

3.3u H

VCC

Capacitance

0.1u F

Distributor	Qty 1
	Digi-Key	$0.02–$1.00
	LCSC	$0.55–$0.81
	Mouser	$0.03–$0.23

Load Weighing Monitoring Device

italodias

2 months

create a load weighing monitoring device for bulk trucks that weighs cargo during the journey and also provides the truck's geospatial location.

copilot

2 months

Using

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Project

Let's start by clarifying a few key design aspects. I’ll ask a total of 3 questions, one at a time.

Question 1:
For the processing unit, would you like to use a board with integrated wireless capabilities (such as an ESP32) or one that requires an add-on for connectivity?

Choose integrated board

Integrated simplifies design

Select integrated wireless

italodias

2 months

I prefer using a board with integrated wireless capabilities, like an ESP32.

copilot

2 months

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Question 2:
For the weight measurement section, would you like to use a standard load cell configuration with an HX711 load cell amplifier (as in the current design), and could you specify the desired capacity and accuracy for the load cells (e.g., high-capacity sensors arranged in a bridge formation)?

Confirm HX711 usage

Specify load cell specs

Choose standard configuration

italodias

2 months

Go with the standard load cell setup using the HX711. I need the sensors to handle approximately 70 tons with high sensitivity.

copilot

2 months

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Question 3:
For the geospatial functionality, would you like to integrate a dedicated, automotive-grade GNSS module (for example, u-blox NEO-6M) that provides high update rates and accuracy, or do you have another specific GNSS module in mind?

Focus on load cell

Optimize circuit

Review resistor values

Improve measurement accuracy

italodias

2 months

Integrate with a dedicated, automotive-grade GNSS module, the u-blox NEO-6M

copilot

2 months

Using

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Based on your responses, here's the proposed design architecture:

Processing & Wireless: Use an ESP32 board with integrated wireless capabilities.
Weight Measurement: Use the standard load cell configuration with an HX711 load cell amplifier. This setup is designed to handle up to 70 tons with high sensitivity.
Geospatial Location: Integrate a dedicated, automotive-grade GNSS module – in this case, the u‑blox NEO‑6M – to provide real‑time position data.

Below is a block diagram representing the system architecture:

This design allows the ESP32 to collect both load measurements (via the HX711 and load cells) and geospatial data (via the GNSS module) while leveraging its integrated wireless capabilities for data transmission during the truck's journey.

Would you like to proceed with creating the schematic changes for this design?

Update schematic details

Inquire wiring guidelines

Request connection layout

italodias

2 months

Yes

copilot

2 months

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Below is a summary of the schematic changes to implement the new design:

ESP32 Integration:
- Add an ESP32-WROOM-32 module (suggested designator: U2).
- Connect the ESP32’s VCC and GND pins to the VCC rail and the common Ground, respectively.
- Reserve two GPIOs on the ESP32 for communication with the HX711 and the GNSS module.
HX711 – ESP32 Connection:
- Using the existing HX711 (U1), wire its PD_SCK pin to one of the ESP32 GPIOs (e.g., GPIO 25) to serve as the clock signal.
- Wire the DOUT pin of the HX711 to another ESP32 GPIO (e.g., GPIO 26) to receive the load cell measurement data.
GNSS Module Integration:
- Add a u‑blox NEO‑6M GNSS module (suggested designator: U3).
- Connect its power pins (VCC and GND) to the same rails as the rest of the circuit.
- Connect the GNSS module’s TX pin to an ESP32 UART RX pin (e.g., GPIO 16) so that the microcontroller can read location data. Optionally, if two‑way communication is required, connect the module’s RX to a free ESP32 UART TX pin (e.g., GPIO 17).
Decoupling and Power Conditioning:
- Add decoupling capacitors (using [C 0603 (1608 Metric)] components) to the power pins of both the ESP32 and the GNSS module to improve supply stability.
Common Ground:
- Verify that all ground pins (from the HX711, ESP32, GNSS module, and decoupling capacitor grounds) are interconnected using the Ground component.

Below is a block diagram of the revised system architecture:

The ESP32 will read load data from the HX711 while also receiving GNSS data from the u‑blox NEO‑6M, then transmit the combined information via its integrated wireless interface.

Would you like to apply these schematic changes?

Confirm and inquire capacitors

Approve and select ESP32 part

Accept and ask wiring details

Confirm design and query noise issues

italodias

2 months

The revised schematic looks solid. Let’s proceed, and can you help me choose a specific ESP32-WROOM-32 variant from the library?

copilot

2 months

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I recommend using the standard ESP32-WROOM-32 module. This variant includes integrated Wi‑Fi and Bluetooth and is widely used in IoT and monitoring applications, making it a reliable choice for your load weighing and geospatial tracking device. Would you like to add this module to your schematic?

Select PCB antenna variant

Opt for integrated flash

Emphasize low power

Confirm standard module

italodias

2 months

I prefer the ESP32-WROOM-32 variant with a PCB antenna for a compact design. Let’s choose that one.

copilot

2 months

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I've selected the ESP32-WROOM-32 with PCB antenna variant, which is ideal for a compact design with integrated wireless features. Would you like to add this component to your schematic as the processing unit?

Add component to schematic

Verify layout guidelines

Review module datasheet

Confirm spacing requirements

italodias

2 months

Yes, please add the ESP32-WROOM-32 to the schematic with its PCB antenna footprint.

copilot

2 months

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Below is a summary of the schematic change for the processing unit update:

ESP32-WROOM-32 with PCB Antenna:
- Replace (or add) the processing unit with the ESP32-WROOM-32 with PCB antenna variant.
- Assign the designator U2.
- Ensure that its power pins (VCC and GND) are properly tied to the power supply and common Ground.
- Reserve appropriate GPIO connections for communication with the HX711 (e.g., clock and data lines) and the GNSS module.

Once you click "Apply Changes," these modifications will be added to your schematic.

Verify power rail

Assign GPIO pins

Check antenna layout

Plan decoupling

italodias

2 months

I need to allocate specific GPIOs for HX711 and GNSS communication. Which pins would you recommend?

copilot

2 months

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I recommend the following GPIO assignments:

For the HX711:
- PD_SCK: GPIO 25
- DOUT: GPIO 26
For the GNSS Module (u‑blox NEO‑6M):
- TX (from GNSS to ESP32 RX): GPIO 16
- RX (from ESP32 TX to GNSS, if needed for two‑way communication): GPIO 17

These assignments free up UART0 (commonly used for programming/debugging) while providing dedicated pins for sensor communication. Would you like to apply these GPIO assignments in your schematic configuration?

Confirm assignments

Update schematic

Check interference

italodias

2 months

These GPIO assignments work. I'll assign 25/26 for HX711 and 16/17 for GNSS.

copilot

2 months

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Great! The following updates will be applied in the schematic configuration:

ESP32-WROOM-32 with PCB antenna (U2):
- GPIO 25 will be connected to the HX711 PD_SCK.
- GPIO 26 will be connected to the HX711 DOUT.
- GPIO 16 will serve as the RX for GNSS data (GNSS TX → ESP32 RX).
- GPIO 17 will serve as the TX if two‑way communication with the GNSS module is needed (ESP32 TX → GNSS RX).

These assignments provide dedicated connections for both the HX711 and the GNSS module while keeping communication channels clear.

Click Apply Changes to update your schematic with these GPIO assignments.

Update schematic

Check signal integrity

Add pull-ups query

Move to power filtering

italodias

2 months

I’ve updated the schematic with these GPIO assignments. Next, how can I verify the net labels are correctly set?

copilot

2 months

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You can verify that your net labels are correctly set by using the integrated Electrical Rule Check (ERC) and Design Rule Check (DRC) tools in Flux. These tools will compare the net names across your schematic and flag any inconsistencies or missing labels.

To do this:

Open the ERC/DRC review tool tab in the right column.
Run the ERC/DRC check to review all nets.
Look for any warnings or errors related to net properties and connectivity.

If you need any further assistance with interpreting the results, let me know!

Inquiry on warnings

Specific checks

Resolving issues

italodias

2 months

I ran the ERC and noticed a few warnings. What are the common issues flagged with net labels?

copilot

2 months

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Common issues flagged with net labels in ERC/DRC reviews include:

Inconsistent Naming:
Net labels with slight variations in spelling, capitalization, or spacing can cause two nets that should be identical to be treated as different.
Unconnected Net Labels:
A net label assigned to a wire or component pin may not be connected to any other instance, leading to a floating or isolated net.
Duplicate/Redundant Net Labels:
Using the same net label in contexts where they shouldn’t be connected, or having more than one net label on a single net, can create unintended connections.
Incorrect or Missing Ground Labels:
Ground nets must be clearly identified (often by linking to a dedicated Ground component). If the connection isn’t consistent, it will be flagged.
Label Connection Errors:
Occasionally, the physical placement of a net label might not actually bridge the intended wires or pins, leading to mismatches between the schematic and the designed connectivity.

Reviewing the ERC/DRC report can help you quickly pinpoint which nets require attention. If you need guidance on how to fix any specific warnings, let me know!

Identify Inconsistencies

Fix Duplicate Labels

Isolated Labels Check

italodias

2 months

next steps in development

copilot

2 months

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Now that your schematic is updated and you've resolved the net label warnings, the typical next phases in the development workflow are:

PCB Layout Design:
- Move to the PCB layout editor.
- Place the components on the board ensuring proper spacing and orientation.
- Begin routing the traces between components according to your schematic connectivity.
Design Rule Checks (DRC) on PCB Layout:
- Run a DRC to make sure routing, spacing, and trace widths meet your design constraints.
Prototype and Testing Preparation:
- Once the PCB layout is finalized and verified, you can prepare the Gerber files and BOM for fabrication and prototype testing.

If you’d like guidance on transitioning to the PCB layout stage or want to address any other aspects (such as footprint placement strategies or routing recommendations), let me know!

Start PCB layout

DRC guidelines

Prototype prep

Des	Net	Des	Net
Trace 0771	Net - (4108 - 8aed)	P2	—
P1	—	Trace 2002	Net - (f11e - f343)
P2	—	Trace d5b2	Net - (2ec3 - 27ab)
P1	—	Trace 5922	Net - (2ec3 - 604a)
P1	—	Trace e728	Net - (f237 - 404d)
P1	—	Trace a057	Net - (f237 - 404d)
P2	—	Trace e391	GND
5	—	Trace ef54	GND
2	—	Trace eeea	Net - (3c80 - 78f5)
Trace 25c4	Net - (f11e - ad4f)	4	—
Trace 2afa	Net - (3c80 - dc9e)	3	—
1	—	Trace 42ac	Net - (f11e - fc72)
Trace 1c7f	Net - (4108 - 8aed)	C	—
Trace 0ad5	Net - (f11e - 5c70)	B	—
E	—	Trace 885e	Net - (3c80 - 78f5)
P2	—	Trace 77ed	Net - (f11e - f343)
Trace 457f	GND	P1	—
P1	—	Trace b888	GND
P1	—	Trace f760	GND
P1	—	Trace 8e23	Net - (f11e - fc72)
P1	—	Trace 9c7a	Net - (f11e - fc72)
P2	—	Trace ccc5	GND
P2	—	Trace 8a99	GND
Trace 87ad	Net - (3c80 - 78f5)	P2	—
P1	—	Trace fe83	Net - (f11e - 147f)
P2	—	Trace bb2c	Net - (8afe - 27ab)
P1	—	Trace c870	Net - (ca2b - 78f5)
P1	—	Trace afe9	GND
P1	—	Trace f760	GND
Trace 62ef	Net - (f11e - fc31)	P2	—
Trace 8c0d	Net - (9e40 - 4d7e)	P1	—
Trace 3722	Net - (9e40 - 4d7e)	P1	—
P2	—	Trace fc15	Net - (9e40 - ddb0)
Trace 67df	Net - (f11e - 147f)	B	—
B	—	Trace e09d	Net - (f11e - 147f)
Trace 73c1	GND	A	—
Trace 4164	GND	A	—
Trace 2e1f	Net - (3c80 - 78f5)	P1	—
Trace 55eb	Net - (3c80 - 78f5)	P1	—
Trace 4614	GND	P2	—
P1	—	Trace e8d9	Net - (3c80 - 78f5)
Trace 55eb	Net - (3c80 - 78f5)	P1	—
P2	—	Trace edda	GND
P2	—	Trace d189	GND
P2	—	Trace e391	GND
5	—	Trace f01f	Net - (f237 - 404d)
2	—	Trace cda6	Net - (ca2b - 78f5)
Trace 0a42	GND	4	—
Trace 8e9e	GND	4	—
3	—	Trace f0b8	Net - (2ec3 - 604a)
Trace be80	GND	1	—
Trace dd26	Net - (f237 - 404d)	P1	—
Trace a057	Net - (f237 - 404d)	P1	—
Trace 5774	GND	P2	—
Trace eed0	Net - (f11e - 147f)	RATE	—
Trace aaf0	Net - (f11e - 5c70)	BASE	—
Trace a183	Net - (3c80 - 78f5)	VSUP	—
Trace b3ec	Net - (9e40 - ddb0)	INB-	—
Trace 600f	GND	AGND	—
Trace c541	Net - (3c80 - dc9e)	DOUT	—
Trace 3722	Net - (9e40 - 4d7e)	INB+	—
PD_SCK	—	Trace f331	Net - (f11e - ad4f)
Trace a16b	Net - (8afe - 27ab)	INA+	—
Trace 5eee	Net - (2ec3 - 27ab)	INA-	—
Trace 53a1	Net - (2ec3 - 27ab)	INA-	—
Trace 78fe	GND	XI	—
Trace 2782	Net - (f11e - f343)	VFB	—
Trace 6f84	Net - (4108 - 8aed)	AVDD	—
Trace e547	Net - (f11e - fc31)	VBG	—
Trace 6f50	Net - (f11e - fc72)	DVDD	—
Trace 9c7a	Net - (f11e - fc72)	DVDD	—
Trace 2452	Net - (f237 - 404d)	P1	—
Trace 6ab6	Net - (4108 - 8aed)	P2	—
P2	—	Trace fa28	Net - (4108 - 8aed)
Trace 0771	Net - (4108 - 8aed)	P2	—
Trace 029f	Net - (4108 - 8aed)	P2	—
Trace 60a4	Net - (2ec3 - 27ab)	P1	—
Trace 5a0c	Net - (8afe - 27ab)	P2	—

adrian95 / SparkFun Load Cell Amplifier - HX711

Schematic

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