Semi-Homemade Remote Head at DVinfo.net

Matt Irwin · October 24th, 2004, 11:32 PM

I recently got my hands on a medium duty pan/tilt head designed for an outdoor security camera, and I want to try and turn it into a hot head that I can mount on a jib arm. I know it works, though I haven't yet tested it myself.

I have the head ONLY, so there's no power or control cables with it. I'm trying to figure out how best to make a pan/tilt control unit that will give me variable speeds as opposed to a fixed "push button" control. I have yet to figure out if the control is logic based or if it's a simple "circuit on, circuit off" method.

The company that makes the head no longer exists, so I've had a lot of trouble finding documentation.
Here's what I know about the head:
Make/Model: Javelin Systems/ JPT35
Power: 24V AC, 8 volt amps
Power Connection: Amphenol 4 pin male recepticle
Control Connection: Amphenol 7 pin male recepticle
Weight: about 25lbs
Payload: 30kg? (I compared this head to others with similar specs and that's what most of them can hold)

Anyone have any ideas? Anyone done something like this before? I'll try to post some pictures of the head when I can.
Thanks!

Rob Lohman · October 25th, 2004, 04:33 AM

If I remember correctly the changing of speeds is done by either
changing the voltage to the motor (linear motor?) or changing
the frequency of the pulses (step motor?). Make sure you do not
give it more voltage than it can take.

Dan Selakovich · October 25th, 2004, 08:48 AM

Hi Matt,

You're going to need a speed controller. Not cheap. Some controllers will control two motors. Others, just one. So if you get the kind that controls one motor, you'll need two: one for the pan motor and one for the tilt motor. Having said all that, I have no idea how you'd connect it into your remote head, or if it would even work. Also, security pan/tilts can be too noisy for dialogue scenes. Something to keep in mind before you spend the cash fixing this thing up!

Dan
www.DVcameraRigs.com

Michael Bernstein · October 25th, 2004, 09:26 AM

Rob wrote:

If I remember correctly the changing of speeds is done by either
changing the voltage to the motor (linear motor?) or changing
the frequency of the pulses (step motor?).

In many cases you can regulate DC voltage (and thus the speed of the motor) with pulse width modulation (PWM). For example, see this article on building a pulse-width modulator.

According to the article, PWM is good because "the pulses reach peak supply voltage and will produce more torque.." but can generate RFI (which the article tells you how to fix).

Stepper motors work by sequentially pulsing different coils around the motor. (This circuit for controlling a stepper motor works with just two coil sets.) If a single step of the motor produces visible movement, it's not suitable for general camera control. You may have to do a lot of physical speed translation (gears or pulleys) and some damping of the jerks to make a stepper motor smooth enough for movie work.

Read this article about stepper motors for more about stepper motors.

Michael

Matt Irwin · October 25th, 2004, 10:52 AM

Wow, great info guys. Thanks!

I've opened up the head (that thing is ironclad!), and I can't tell whether the motors are stepper or linear. I'll have to do some more research on the make and model of the motors. There are two motors, so more $ in the speed controller dept? I'd like to DIY as much as I can, but if it ends up not working at all... Hey! It was free to begin with.

Also, the head is 24 volts *AC* not DC, in case that makes any difference.
I'll post any updates on this project in case anyone is interested.

Thanks again for the help!

October 24th, 2004, 11:32 PM	#1
Matt Irwin Major Player Join Date: Jul 2004 Location: Los Angeles, CA Posts: 327	Semi-Homemade Remote Head I recently got my hands on a medium duty pan/tilt head designed for an outdoor security camera, and I want to try and turn it into a hot head that I can mount on a jib arm. I know it works, though I haven't yet tested it myself. I have the head ONLY, so there's no power or control cables with it. I'm trying to figure out how best to make a pan/tilt control unit that will give me variable speeds as opposed to a fixed "push button" control. I have yet to figure out if the control is logic based or if it's a simple "circuit on, circuit off" method. The company that makes the head no longer exists, so I've had a lot of trouble finding documentation. Here's what I know about the head: Make/Model: Javelin Systems/ JPT35 Power: 24V AC, 8 volt amps Power Connection: Amphenol 4 pin male recepticle Control Connection: Amphenol 7 pin male recepticle Weight: about 25lbs Payload: 30kg? (I compared this head to others with similar specs and that's what most of them can hold) Anyone have any ideas? Anyone done something like this before? I'll try to post some pictures of the head when I can. Thanks! __________________ Matt Irwin DP / matt.irwincine.com

October 25th, 2004, 04:33 AM	#2
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	If I remember correctly the changing of speeds is done by either changing the voltage to the motor (linear motor?) or changing the frequency of the pulses (step motor?). Make sure you do not give it more voltage than it can take. __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

October 25th, 2004, 09:26 AM	#4
Michael Bernstein Regular Crew Join Date: Sep 2004 Location: Brooklyn, NY Posts: 114	Rob wrote: If I remember correctly the changing of speeds is done by either changing the voltage to the motor (linear motor?) or changing the frequency of the pulses (step motor?). In many cases you can regulate DC voltage (and thus the speed of the motor) with pulse width modulation (PWM). For example, see this article on building a pulse-width modulator. According to the article, PWM is good because "the pulses reach peak supply voltage and will produce more torque.." but can generate RFI (which the article tells you how to fix). Stepper motors work by sequentially pulsing different coils around the motor. (This circuit for controlling a stepper motor works with just two coil sets.) If a single step of the motor produces visible movement, it's not suitable for general camera control. You may have to do a lot of physical speed translation (gears or pulleys) and some damping of the jerks to make a stepper motor smooth enough for movie work. Read this article about stepper motors for more about stepper motors. Michael __________________ Michael Bernstein, actor & film maker. 10 films in 10 weeks: www.amplecatnap.com

October 25th, 2004, 10:52 AM	#5
Matt Irwin Major Player Join Date: Jul 2004 Location: Los Angeles, CA Posts: 327	Wow, great info guys. Thanks! I've opened up the head (that thing is ironclad!), and I can't tell whether the motors are stepper or linear. I'll have to do some more research on the make and model of the motors. There are two motors, so more $ in the speed controller dept? I'd like to DIY as much as I can, but if it ends up not working at all... Hey! It was free to begin with. Also, the head is 24 volts AC not DC, in case that makes any difference. I'll post any updates on this project in case anyone is interested. Thanks again for the help! __________________ Matt Irwin DP / matt.irwincine.com

October 25th, 2004, 08:48 AM	#3
Dan Selakovich Major Player Join Date: Jun 2004 Location: Los Angeles, CA Posts: 220	Hi Matt, You're going to need a speed controller. Not cheap. Some controllers will control two motors. Others, just one. So if you get the kind that controls one motor, you'll need two: one for the pan motor and one for the tilt motor. Having said all that, I have no idea how you'd connect it into your remote head, or if it would even work. Also, security pan/tilts can be too noisy for dialogue scenes. Something to keep in mind before you spend the cash fixing this thing up! Dan www.DVcameraRigs.com