# Habistat Dimming Thermostat Buzzing



## Geom (Sep 29, 2013)

Hi all,

I'm using a Habistat Dimming Thermostat with a 60w spot lamp as a primary heat source for my Blue Tongue Skink setup. Problem is when it begins adjusting the power to the lamp it begins producing an audible buzzing sound. I'm aware this is expected to happen from the Dimming unit but I'm not so sure about the lamp itself.

I've seen a few posts on here regarding the problem, but I've not found a real solutions to it. As far as I know its been doing this all the time I've had the unit but over the summer I've noticed it a bit more as its applying more dimming to the lamp to control the temperature.

Just wondered if you guys had any suggestions, or other means of heat I can use instead. I hate to think the buzzing could be bugging the skink.

All the best,


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## Geom (Sep 29, 2013)

Any ideas?


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## LFBP-NEIL (Apr 23, 2005)

if the actual lamp is buzzing and not the thermostat try screwing the bulb in a bit tighter generally a buzzing noise would indicate a bit of arcing going on in the holder, sometimes the bulbs "ring" or whistle when they are about to go pop.


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## Geom (Sep 29, 2013)

It seems to only buzz when its under a low load (ie when its reached the set temperature and begins dimming), I'll try screwing the bulb in tighter later today. Cheers


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## Electro1 (Oct 3, 2013)

Hi,

The reason for the bulb making a buzzing sound when the stat starts to dim the bulb is due to Habistat not including any noise suppression on the output of the stat.

A dimming stat works by chopping up the AC waveform and waiting for a set period of time before turning the output on. This happens very quickly. It happens 100 times per second to be exact. 

Due to the lamp being turned on part way through a wave cycle it causes an inrush of current and creates electrical noise. This is usually captured in whats know as a toroid coil. it acts as a type of reservoir to capture the excess current and release it slowly back to the bulb, this smooths the output out.

Without the toroid in place you get whats known as filament sing. Its very common if you look around on the net. Cheap DJ equipment for example suffers the same issues.

Just to put your mind at rest, this does not make the stat in any way unsafe to use. Its just an annoying sound coming from the bulb. You will notice it may get louder the dimmer the bulb becomes.

Hope this answer helps, I tried to answer it in as basic terms as possible but with all the info there for you.


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## Geom (Sep 29, 2013)

Awesome explanation, thanks.

I'm assuming theres nothing that can be done since its the way the Habistat is designed, guess everyone has the same issue.

Don't suppose theres any similar products that do have some kind of noise suppression included?

Cheers.


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## Electro1 (Oct 3, 2013)

No Problem,

Yeah its just how there made. Some people experience noise more than others, it depends on the quality of the bulb, age etc.

Microclimate dimming stats have suppression built in.


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## LFBP-NEIL (Apr 23, 2005)

What about the I-stats - do they have suppression built in?


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## Electro1 (Oct 3, 2013)

The iSTATs don't need noise suppression built in, they are Pulse stats and use and opto triac with a built in zero crossing circuit. This allows them to turn the power to the heater on exactly at zero crossing when the current is zero. 

The iSTAT also has a snubber circuit on the triac output to further eliminate electrical noise. A trait that microclimate/Komodo also have.


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## Geom (Sep 29, 2013)

Electro1 said:


> No Problem,
> 
> Yeah its just how there made. Some people experience noise more than others, it depends on the quality of the bulb, age etc.
> 
> Microclimate dimming stats have suppression built in.


Sorry about the late reply, been busy.

I think I'll switch to a Microclimate stat and see how it goes.

Cheers for all the help


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