Post Reply 
 
Thread Rating:
  • 0 Votes - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
PWM alternative?
Author Message
Scorp76 Offline
Member
***

Posts: 51
Joined: Aug 2008
Reputation: 0
Post: #1
PWM alternative?
Would a Rheostat not perform the same function as a PWM? Has anyone out there tried this yet?
08-21-2008 08:54 AM
Find all posts by this user Quote this message in a reply
JonnyBravo Offline
Member
***

Posts: 62
Joined: Jul 2008
Reputation: 0
Post: #2
RE: PWM alternative?
A Rheostat *could* perform the same function as a PWM would; However, it does so in a very inefficient matter. Basically, a rheostat is a variable, high wattage resistor - used to be used as a light dimmer many years ago before the new style of light dimmers came to be (which now is a PWM).

Since most HHO generators pull between 10 and 30 amps, a rheostat would generate a lot of heat to be able to control that much power. I think it would have a big negative impact on your net gain of energy that you are going for with a HHO system. I think it's definitely worth going the PWM method because your efficiency would be much higher.
08-21-2008 10:01 AM
Find all posts by this user Quote this message in a reply
wgc Offline
Member
***

Posts: 25
Joined: Jul 2008
Reputation: 0
Post: #3
RE: PWM alternative?
Scorp76 Wrote:Would a Rheostat not perform the same function as a PWM? Has anyone out there tried this yet?

No, A PWM is a Pulse Width Modulator. What it does is send DC voltage in spikes at 100 times per second. What you need is here:

http://www.bakatronics.com/shop/item.aspx?itemid=581
08-21-2008 11:16 AM
Find all posts by this user Quote this message in a reply
colchiro Offline
Moderator
*****

Posts: 3,265
Joined: Feb 2008
Reputation: 11
Post: #4
RE: PWM alternative?
Think of a PWM a similar to a light dimmer.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
08-21-2008 05:29 PM
Find all posts by this user Quote this message in a reply
wgc Offline
Member
***

Posts: 25
Joined: Jul 2008
Reputation: 0
Post: #5
RE: PWM alternative?
colchiro Wrote:Think of a PWM a similar to a light dimmer.

No, It is not like a dimmer. A dimmer decreases voltage.
A PWM's current is what changes. That's why they are used on motors.
08-21-2008 05:51 PM
Find all posts by this user Quote this message in a reply
colchiro Offline
Moderator
*****

Posts: 3,265
Joined: Feb 2008
Reputation: 11
Post: #6
RE: PWM alternative?
In layman's terms, light dimmer is a good enough.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
08-21-2008 06:23 PM
Find all posts by this user Quote this message in a reply
rudagray Offline
Collaboration is the Key to Success!
***

Posts: 308
Joined: Jul 2008
Reputation: 1
Post: #7
RE: PWM alternative?
colchiro Wrote:In layman's terms, light dimmer is a good enough.

A light dimmer that is turned on and off at 100 times per second? or much more I think I saw 20kHz.. 20,000 times per second... At that rate does the cell actually see the drop...

I was also reading that a multiple series unit or a neutral plate design that both lower voltage between plates negates the need for the PWM- Is that correct...why?
(This post was last modified: 08-21-2008 07:21 PM by rudagray.)
08-21-2008 07:20 PM
Find all posts by this user Quote this message in a reply
wgc Offline
Member
***

Posts: 25
Joined: Jul 2008
Reputation: 0
Post: #8
RE: PWM alternative?
rudagray Wrote:
colchiro Wrote:In layman's terms, light dimmer is a good enough.

A light dimmer that is turned on and off at 100 times per second? or much more I think I saw 20kHz.. 20,000 times per second... At that rate does the cell actually see the drop...

I was also reading that a multiple series unit or a neutral plate design that both lower voltage between plates negates the need for the PWM- Is that correct...why?


A popular theory is that the voltage spikes allow the electrolysis cycle before the current ramps up. Then it shuts off, stopping the current flow and also allowing the bubbles to clear for the next exchange, kind of like an agitation cycle.

Voltage is what causes the electrolysis. Amperage get wasted as heat. Using a pwm will always be better than direct voltage for HHO.
08-22-2008 03:56 AM
Find all posts by this user Quote this message in a reply
waterboy1 Offline
Member
***

Posts: 35
Joined: May 2008
Reputation: 0
Post: #9
RE: PWM alternative?
wgc Wrote:
rudagray Wrote:
colchiro Wrote:In layman's terms, light dimmer is a good enough.

A light dimmer that is turned on and off at 100 times per second? or much more I think I saw 20kHz.. 20,000 times per second... At that rate does the cell actually see the drop...

I was also reading that a multiple series unit or a neutral plate design that both lower voltage between plates negates the need for the PWM- Is that correct...why?


A popular theory is that the voltage spikes allow the electrolysis cycle before the current ramps up. Then it shuts off, stopping the current flow and also allowing the bubbles to clear for the next exchange, kind of like an agitation cycle.

Voltage is what causes the electrolysis. Amperage get wasted as heat. Using a pwm will always be better than direct voltage for HHO.

This sounds interesting. Is anyone on this forum using one now?? and what are results? Thanks
08-22-2008 04:59 AM
Find all posts by this user Quote this message in a reply
wgc Offline
Member
***

Posts: 25
Joined: Jul 2008
Reputation: 0
Post: #10
RE: PWM alternative?
waterboy1 Wrote:This sounds interesting. Is anyone on this forum using one now?? and what are results? Thanks

I am currently using on with the 6 pack configuration.
Direct DC connection had a draw of 12 to 15 amps.
With the PWM, the draw is now .6 amps.

The 6 pack is wired in this configuration:
O-O-O--(+)
| | |
O-O-O--(-)

Soon I will migrate to a single bath, multi-plate cell design.
A time permits...
(This post was last modified: 08-22-2008 05:11 AM by wgc.)
08-22-2008 05:09 AM
Find all posts by this user Quote this message in a reply
Post Reply 


Forum Jump:


User(s) browsing this thread: 1 Guest(s)