# Power Supply considerations for simple hardware nodes

**URL:** <https://discourse.nodered.org/t/power-supply-considerations-for-simple-hardware-nodes/100021>\
**Category:** Share Your Projects\
**Created:** [25 December 2025 07:29 UTC](https://discourse.nodered.org/t/power-supply-considerations-for-simple-hardware-nodes/100021 "2025-12-25T07:29:55Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![dynamicdave](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dynamicdave/32/96_2.png) [@dynamicdave](https://discourse.nodered.org/u/dynamicdave)\
**Post date:** [25 December 2025 07:29 UTC](https://discourse.nodered.org/t/power-supply-considerations-for-simple-hardware-nodes/100021/1 "2025-12-25T07:29:55Z")

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Like many makers, I build simple hardware nodes using ESP32 devices and power them from low-voltage supplies, such as batteries or standard AC/DC adapters (e.g., mobile phone chargers).

My regulator of choice is the ubiquitous **LD33CV** (also known as **LD1117V33C** ), a Low Dropout (LDO) linear regulator. It comes in a 3-pin TO-220 package, provides a fixed **3.3 V output up to 800 mA** , and features low dropout voltage and minimal noise—making it ideal for battery-powered applications.

 ![wed_LD33CV.PNG](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/e/9/e993b1d255ab56070499d639ff9aaf1a26972929.jpeg)  
Typically, I drive it from a **5 V input** , supplied by an AC/DC power unit like this:  
 ![wed_AC_DC](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/c/0/c070ff0e781d4d32ab0d258910bbd1f2035602bc.png)  
This setup has served well in several PCB-based nodes. However, as with all linear regulators, **efficiency drops as input voltage increases**. For example:

- **5 V input → 3.3 V output:** ~66% efficient
- **12 V input → 3.3 V output:** ~27.5% efficient, with ~0.87 W of heat dissipated

This low efficiency is particularly noticeable in my greenhouse nodes powered by a 12 V mobility scooter battery, which only lasts a couple of months before needing a recharge.

To improve efficiency, I have started using low-cost **Switched Mode Power Supply (SMPS) modules**, such as the **DD4012SA**. These modules are inexpensive and can achieve efficiencies of **80–95%**.

 ![DD4012SA.PNG](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/6/4/64405fb74a626e037eefd54b1dd74b0e66e9cac5.jpeg)  
The trade-off is **switching noise** , typically in the **100 kHz–3 MHz** range, which manifests as voltage ripple on the output. How much ripple matters depends on the load. ESP32s, Raspberry Pis, and Arduinos generally work fine from an SMPS, but some sensitive ADCs or sensors may require extra filtering.

A common solution is a **SMPS + LDO combo** , which combines the best of both worlds:

- **SMPS:** efficiently drops voltage (e.g., 12 V → 5 V)
- **LDO:** smooths out noise (e.g., 5 V → 3.3 V)  
 ![wed_combo](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/3/c/3cfecdaa9e19ec473bf127bedd946ff102261b29.png)

I plan to implement this in my next PCB-based node using a **5 V DD4012SA** followed by an **LD33CV**. My design will include **two 3-pin female headers** for the combo. For indoor applications with a 5 V supply, the SMPS can be omitted and replaced with a simple wire link, making the same PCB suitable for multiple scenarios.

 ![wed_schematic](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/6/9/69ac7228cf0adb127cdce7730c07711bca50e545.png)  
 ![wed_2D](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/e/e/ee8a8307f855b9f60596e7a6b0616569553a4a62.png)  
 ![wed_3D](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/f/a/fa6b559337d96f18a8e00207e9448b99a386e3e6.png)

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**Author:** ![Paul-Reed](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/paul-reed/32/66906_2.png) [@Paul-Reed](https://discourse.nodered.org/u/Paul-Reed)\
**Post date:** [25 December 2025 09:19 UTC](https://discourse.nodered.org/t/power-supply-considerations-for-simple-hardware-nodes/100021/2 "2025-12-25T09:19:26Z")

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I've just bought some of the below, which are only rated at 1A (5W), but sufficient for some home constructed modules. Currently on clearance at IKEA for £1 each!

[https://applink.ikea.com/tY8M9r9M4w--50538729--gb--en](https://applink.ikea.com/tY8M9r9M4w--50538729--gb--en)

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**Author:** ![dynamicdave](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dynamicdave/32/96_2.png) [@dynamicdave](https://discourse.nodered.org/u/dynamicdave)\
**Post date:** [25 December 2025 09:21 UTC](https://discourse.nodered.org/t/power-supply-considerations-for-simple-hardware-nodes/100021/3 "2025-12-25T09:21:16Z")

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Oh that looks nice and cheaper than the ones I get from CPC-Farnell.

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**Author:** ![krambriw](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/krambriw/32/5429_2.png) [@krambriw](https://discourse.nodered.org/u/krambriw)\
**Post date:** [25 December 2025 10:02 UTC](https://discourse.nodered.org/t/power-supply-considerations-for-simple-hardware-nodes/100021/4 "2025-12-25T10:02:20Z")

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IKEA is IKEA... 💪 🇸🇪

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**Author:** ![jbudd](https://avatars.discourse-cdn.com/v4/letter/j/5f8ce5/32.png) [@jbudd](https://discourse.nodered.org/u/jbudd)\
**Post date:** [25 December 2025 13:03 UTC](https://discourse.nodered.org/t/power-supply-considerations-for-simple-hardware-nodes/100021/5 "2025-12-25T13:03:56Z")

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i need some more USB PSUs but I'm not prepared to walk 3 miles round Ikea to buy them, even at £1 each!

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**Author:** ![TotallyInformation](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/totallyinformation/32/31_2.png) [@TotallyInformation](https://discourse.nodered.org/u/TotallyInformation)\
**Post date:** [26 December 2025 17:36 UTC](https://discourse.nodered.org/t/power-supply-considerations-for-simple-hardware-nodes/100021/6 "2025-12-26T17:36:29Z")

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🤣 But you get to try out all the beds! And your partner gets all those furniture ideas that you will never implement! And don't forget the meatballs lunch if you time it right. 😉

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**Author:** ![dynamicdave](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dynamicdave/32/96_2.png) [@dynamicdave](https://discourse.nodered.org/u/dynamicdave)\
**Post date:** [27 December 2025 09:39 UTC](https://discourse.nodered.org/t/power-supply-considerations-for-simple-hardware-nodes/100021/7 "2025-12-27T09:39:01Z")

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Just taken advantage of [JLCpcb's](https://jlcpcb.com/) special offer to build another PCB.

 ![thur_moisture_PCB](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/3/6/36f4c24d006ac3851cd2641931cf1e6ec094ee47.png)  
This particular board will be a **try out** of my power supply **COMBO** idea.  
Here's a detailed view of the area of the board where H3 and H3\_A are located.  
 ![friday_power_options](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/2/9/293b3fc4225af233cfd4c37a32beb9a6f6fa92a3.png)  
**12V Power Source**  
When the board is powered from a 12 V source (such as a mobility scooter or car battery), an SMPS module **DD4012SA (5 V output)** is fitted to **H3** , and an **LD33CV LDO regulator** is fitted to **H3\_A**. This combination provides **very low output noise** , with an overall efficiency of approximately **53–63%**.

If the **LD33CV is removed** and replaced with a **wire link** , and the **DD4012SA is replaced with a 3.3 V output version** , overall efficiency improves significantly to around **80–95%** , at the cost of increased **output ripple voltage**.

A third option is to **retain the LD33CV** and **remove the SMPS** , replacing it with a **wire link**. This configuration offers **very low noise** , but results in **poor efficiency (≈27.5%)** and **significant power dissipation** in the linear regulator.

* * *

**5V Power Source**  
When powered from a 5 V supply, two practical options are available.

The first option is to fit a **DD4012SA (3.3 V output)** to **H3** and a **wire link** to **H3\_A**. This provides a high efficiency of approximately **80–95%** , again at the expense of increased **output ripple**.

The second option is to **retain the LD33CV** and replace the SMPS with a **wire link**. In this case, efficiency drops to approximately **66%** , but the output rail benefits from **very low noise**.