PWM Dimmer for CCD-FLAT box, 30kHz

Dimmer for regulating the flat field box

When regulating a FlatFieldBox (FFB) lighting for astronomical CCD cameras, we need vibration-free AND extremely short exposure times in the (sub) millisecond range. Unfortunately, conventional dimmers cannot be considered for this, but only a so-called PWM with an on and off frequency of 25 kHz or even faster!

What is PWM and why do we use it?

In theory, it would be enough to reduce the voltage by means of an ohmic resistor if we wanted to dim light bulbs rather than LEDs. However, we absolutely need a dimmer with pulse-width modulation that regulates the time interval in which the full voltage is effective: the regulating instrument is switched on and off in quick succession.

Depending on the switch-off / switch-on frequency, various accessories can be operated: for a heating jacket, switching it on and off once per second would be enough, or even less, because its inertia is very high. In everyday life, around a hundred cycles per second are sufficient for such dimmed LED lights (e.g. living room lighting), because the human eye can hardly perceive the flickering from a frequency of 25 Hz. For FlatFieldBox (FFB), which were built for astronomical CCD cameras, at least 25kHz is required in order to be able to guarantee evenly illuminated surfaces even in a short lighting time.

Technical specifications

• Input: RCA and 5.5 / 2.1mm (note polarity: center positive)
• Output: RCA and 5.5 / 2.1mm (note polarity: center positive)
• Frequency: over 30 kHz, typically 31-36 kHz (guaranteed to switch on and off more than 30,000 times per second)
• Maximum current: 3A
• Input voltage range: 12-24V
• Cable length: with additional cable 230cm (included)
• Weight: 130 grams
• RCA and 5.5 / 2.1mm plugs can be used

Because of the different FlatFieldBox (FFB) manufacturer specifications, we offer a combination solution: both RCA-RCA and 5.5 / 2.1 - 5.5 / 2.1mm connection possible. The total length of the connected cables (including the dimmer unit) is around 230cm.