30w low voltage PWM controller

[Michael GilliganParticipant @michaelgilligan61133]

These little ‘1803BK’ modules are all-over ebay, etc. at a range of prices … but I wondered what chip they used.

https://www.ebay.co.uk/itm/267127192017

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All was revealed when I found this page:

https://quagmirerepair.com/pwm-low-voltage-dc-motor-speed-controller-1-8-15vdc-30-watt-1803bk.html

Yes folks, in mid-2025 the 555 timer is still alive and kicking

MichaelG.

[BazyleParticipant @bazyle]

My first task on starting work in ’77 was something similar with a555 and a 2N3055. Not sure what driver trany I used but 2N2926 was just becoming popular.

[noel shelleyParticipant @noelshelley55608]

In any history of electronics, the 555 and the 2N3055 will always be mentioned. Happy days ! Noel.

[Michael GilliganParticipant @michaelgilligan61133]

Post #63 here:

https://www.hobby-machinist.com/threads/another-treadmill-motor-speed-controller-conversion-thread.86117/page-7

is very informative.

MichaelG.

[Robert Atkinson 2Participant @robertatkinson2]

A lot of manufacturers have stopped production of the older “staple” devices like the 555  and even basic 78xx/79xx voltage regulators. Probably a combination of low demand and reducing capacity for the older silicon production processes. Sometimes the manufacturer will switch to a newer silicon process which can have unforseen consequences. Mant years ago I was asked to investigate a drive interface for 20 pneumatic solenoid valves. It was driven by a PC and bothe the hardware and software had been in use for years with no failures. Suddenly customers started complaining of inconsistent operation. This was costing them significant amounts of lost production. Long story short the driver IC manufacturer had changed to a “better” silicon process. They didn’t change the part number or even revision of the chip as it fully met the published specification. The new chip was actually much faster than the old one. This alone was not an issue. The PC based software was the other half. It had been poorly written and didn’t meet the required timing of the signals that were input to the ICs. The old chips were too slow to notice but the new ones weren’t and mis-interpreted some sequences. The chip manufacturer eventually admitted they had changed the silicon. Re-writing the software with correct timing fixed the issue and actually increased operating speed of the whole process increasing production.  Apparently the original software writer had trouble  with it as first produced years previously but rather than find the actual problem and fix it they just slowed it down until it worked!

For a PWM driver these days I’d use a PIC microprocessor. This allows advanced features such as slow start on power up or a no-power release. An advanced 8 pin divice like a PIC12F1822 has built in precision oscillator, hardware PWM and an analog to digital converter (ADC). The ADC can be used to read a potentiometer for a classical hardware “knob” interface.
The PIC is about the same price as a 555.

Robert.

[John HaineParticipant @johnhaine32865]

Ah Robert, but the PIC won’t support that neat 555 “feature” that crowbars the supply rails when it switches!

[Robert Atkinson 2Participant @robertatkinson2]

That was ony the original. Hopefully they are using the CMOS version 🙂

[SillyOldDufferModerator @sillyoldduffer]

I’ve long had a love-hate relationship with the NE555!   Pure genius with some gotchas.   The original chip tended to crowbar the supply line when the output switched, causing hard to diagnose faults.  The later CMOS 555 fixed that.   The NE555 is remarkably versatile, used in a multitude of clever circuits, but some applications push it too far – they work, but not very well.  Not accurate as a timer, nor do they cope well with long periods.   And a lot of extra electronics are needed to do complex control.

In contrast most microcontrollers support the various shades of PWM on several pins, and many are powerful enough to convert G-code into multi-axis motor movements as well.  An NE555 does only one PWM, whilst a microcontroller does ‘n’ plus complex control.    And,  as Robert says, because a smart PWM capable microcontroller costs about the same as an NE555, so the NE555 is being gradually squeezed out.

Bottom line, whilst the NE555 is super-clever and excellent for basic electronics, it’s limited!  Learn to program if anything complicated is needed, now or in the future.

PIC vs the alternatives is an interesting debate.  I’m prejudiced against PIC because it wasn’t beginner friendly when I first tried it.   Last time I checked, about 5 years ago, PIC was still harder to use than it need be.  Pity, because PIC chips are functionally very good.   It’s just easier to get the same results from an Arduino, Nucleo or any other mbed platform.   Now I’ve learned Arduino and mbed, PIC would have to do something very special to lure me away.  Unlikely to happen.

Dave

[Robert Atkinson 2Participant @robertatkinson2]

I started with PICs before Arduino etc back in the mid 90’s. Iv’e never got on with C but have found PicBasic (laterly PicBasicPro https://pbp3.com/ there is a free version for hobbyists) to be more than capable and you can also imbed a bit of machine code if you need to. It’s complied so fast and doesn’t eat resource with an operating system or interperter. You can easilly access hardware and registers but there are built commands for common stuff.
One thing that put me off the original Ardunio UNO was that they offset the two 0.1″ headers by half a pitch. This means you can’t mount it directly on a standard prototyping board or eurocard. Or build a “hat” on protoboard. Why did they do that? The only thing I can think of was to force you to buy their hats and interface boards. Until the clones came out at least.

PICs are cheap, capable and can be used in minimal systems. Another big advantage is that they are electrically quiet compared to the more powerful modules. This is important if you want to meet interference regulations. I must admit though that Microchips tools and support seem to have gone downhill since they bought out Atmel and Microsemi.

I’m a hardware person not a programmer and got annoyed when the “proper” progrmmers demanded more memory or more powerful processors because they were using software to do tasks that the chip had hardware to do e.g. PWM and serial communications and the external circuitry was designed to use. Often I’d alread proved the prototype with PicBasic code.

Robert.

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

……
One thing that put me off the original Ardunio UNO was that they offset the two 0.1″ headers by half a pitch. This means you can’t mount it directly on a standard prototyping board or eurocard. Or build a “hat” on protoboard. Why did they do that? The only thing I can think of was to force you to buy their hats and interface boards. ….

Indeed.  Apparently the reason is that they were up against a manufacturing deadline doing a respin of the layout and made a mistake, offsetting some of the pins along one side.  Only found out when the first batch of boards came back and they had to get them out of the door ‘cos no money to correct.

[John HaineParticipant @johnhaine32865]

I’ve got two PIC programmers and two batches of chips, and I want to load the picPET code but as Robert and Dave say they aren’t that easy to get to grips with compared with Arduino – and now RPi Pico.

[Robert Atkinson 2Participant @robertatkinson2]

What programmers and chips do you have? Programming a PicPet should be straight forward. You don’t need to write any code or even compile anything. I can help you with this.

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