17 replies to this topic

[Mark Onofri]

Here's something a lot different that you don't see everyday.

I'll post more pics shortly.

 

 

[Mark Onofri]

I'll post the instructions later.
 
Anyone ever used one of these?
 
Looks and feels like #5 of solder on the connections.
 

[Bill from NH]

I never owned one, but I think they were popular in the '90s. The one in your photos looks new. Is it yours?

[Bill Seitz]

I haven't used one, but this is basically a diode controller using bridge rectifiers. Diode controllers use a series string of diodes using the .6V voltage drop across each one to create a throttle step. Because bridge rectifiers have diodes arranged in both polarities, they enable the Omni to work in either polarity. Realize that this is a very early entry into electronic controllers noting that it's only 9 bands and was primarily competing with resistor controllers. It may have seemed like it was adjusting to all levels of motors because I'm sure it was better than the resistor controllers in this respect. However, diodes still increase voltage drop as current increases, so they aren't as effective in adjusting for different motors as a transistor controller with typical sensitivity control. The sensitivity control also lacks the resolution and variability of a transistor controller, since the sensitivity is being changed by switching additional diodes in and out of the circuit. A bridge rectifier having 2 diodes in series offers a 1.2V step. That's pretty coarse resolution. Of course, compared to a resistor controller that likely had no sensitivity control and was greatly effected by changes in load current, the Omni could be a big improvement. Today, it's far surpassed by transistor controllers. I'd relegate it to a conversation piece and historic collectible.

 

Of course, I was recently told of a wing car racer that's still using a 7-band Difalco. I didn't know Jim made a 7-band controller - missed that one.

[slotcarone]

I have a Cidex Omni. A similar but different design. They were used with a Parma Turbo controller and you converted it to the Cidex. We sold many of them and did the conversion at Westchester Raceway back in the '90's. A great design that myself and many others used for flexi and up to Group 27 classes. I used mine for many years when we first started Retro racing. I had an adjustable brake on it. Still works great.

[Mark Onofri]

The adjustable brake is something that I've been hoping will be better when using the new bread of insanity powerful magnets. Having learned to negotiate(sometimes)the corners by costing into them,I've not been able to do that with these magnets.

Yes, Billnh,I purchased it new but I've yet to use it. I believe that my >=.7ohm external controller that had been my favorite,with a lot of sentamental value has been stolen,so I dug this up looking for it.

[Jim Difalco]

I haven't used one, but this is basically a diode controller using bridge rectifiers. Diode controllers use a series string of diodes using the .6V voltage drop across each one to create a throttle step. Because bridge rectifiers have diodes arranged in both polarities, they enable the Omni to work in either polarity. Realize that this is a very early entry into electronic controllers noting that it's only 9 bands and was primarily competing with resistor controllers. It may have seemed like it was adjusting to all levels of motors because I'm sure it was better than the resistor controllers in this respect. However, diodes still increase voltage drop as current increases, so they aren't as effective in adjusting for different motors as a transistor controller with typical sensitivity control. The sensitivity control also lacks the resolution and variability of a transistor controller, since the sensitivity is being changed by switching additional diodes in and out of the circuit. A bridge rectifier having 2 diodes in series offers a 1.2V step. That's pretty coarse resolution. Of course, compared to a resistor controller that likely had no sensitivity control and was greatly effected by changes in load current, the Omni could be a big improvement. Today, it's far surpassed by transistor controllers. I'd relegate it to a conversation piece and historic collectible.

 

Of course, I was recently told of a wing car racer that's still using a 7-band Difalco. I didn't know Jim made a 7-band controller - missed that one.

Bill, you are cheating me out of 3 wiper bands! I made 10 band external resistor controllers. Back in the early 1990's when the Omni came out the owner asked me to build them for him while I was already building my own external resistor controllers. I told him I would consider it and he gave me one of the original units to play with. I had no intention of being his employee and I still have the unit to this day. His company lasted about 3 years or so.

[Mark Onofri]

What's your take on it Jim?

[Bill Breck]

The adjustable break is something that I've been hoping will be better when using the new bread of insanity powerful magnets. Having learned to negotiate(sometimes)the corners by costing into them,I've not been able to do that with these magnets.
Yes Billnh,I purchased it new but I've yet to use it. I believe that my >=.7ohm external controller that had been my favorite,with a lot of sentamental value has been stolen,so I dug this up looking for it.

 

Try turning the brake all the way off to get maximum coast and then adjust it upwards if you feel you need more brakes. This is what I used to do for the Wednesday night LMP race at Speedy's. 

[Bill Seitz]

Jim, I was not meaning to cheat you out of 3 bands. I'm familiar with 10 bands as the least number on a Difalco controller, and that was a while ago. Recently I was told of someone with an old 7-band Difalco, something I wasn't aware even existed. Maybe it wasn't one of yours.

 

I know the high performance resistor controllers had 6 - 10 bands, and it was in this market that the Omni was competing. I've never understood the fascination with strings of series-connected diodes to create stepped voltage drop. For an engineer, it seemed a better solution to use a transistor, and suitable high current transistors have been around since the 70's. I surmise that perhaps it was not knowing how to use the transistor. As an engineer, I skipped over diodes and went straight to transistors. The Cidex controllers don't seem to have been too popular and didn't stay in the market long.

 

Unfortunately, neo and cobalt magnets are strong enough that the dynamic braking circuit may not be needed. I often turn brakes off with a switch, and still the car has more brakes than I may need. The adjustable brakes on the Omni will likely do no better than what we already have with a brake pot, since the brakes can be too strong with the circuit switched completely off. This is where "Anti-brake" comes into play. "Anti-brake" disconnects the brake circuit and instead applies some throttle to the car when the controller wiper is on "brake". That's the solution to too much brake. I've learned to keep low throttle applied and not engage braking to overcome "too much brakes", but "Anti-brake" may be easier for some to use.

[Mark Onofri]

Thanks, I'll try those suggestions.
This controller will look good on the wall. Art for arts sake.

[Mr. M]

Back in the 80s when we were running G27, I tried an external resistor vs diode vs last state of the dual barrel resistor with heat sinks. The diode controller was smoother and more forgiving. This was probably in the 8-10 band wiper timeframe. I think this is what made them popular for a time. 

[Jim Difalco]

Bill, I was joking! The Omni was very popular as far as you could buy his module and replace your Parma resistor with it. The owner, Steve I think was his name, had some sort of business making equipment for telephone switching systems so maybe his diode useage came from that area of expertise?

[Jim Difalco]

What's your take on it, Jim?

 

Wall art is about right. Ten wiper bands just do not cut it any more. 

[Bill Seitz]

Recently I was going through a storage bin and found some of the 1 ohm or less Parma Turbo resistors I used to use, and they only have 6 or 8 turns. Today, the 2, 17-band Difalco boards I still have are just adequate, and I prefer 30 or more bands. How did we ever manage with so few steps in our controllers? Partly it was that we were mostly running on fast tracks, and the biggest reason I suspect is that's all we had and didn't know any better.

 

Having all the motor current pass through the wiper and bands demanded heavy duty wiper elements and wiring from the track to the handle. Not having to do that anymore is a major improvement.

[Mark Onofri]

I just hope that I can find the previously mentioned >=.7 ohm controller. It was built for me by my good friend Gordy Root. Jim, I believe you knew him. It was built in 87 or so. By the 90's, I should have listened to Bill Slater and Gordy and bought a DiFalco. I've got a few more to post, I'll do that in under a different title.

[Jim Difalco]

Yes, I knew Gordy

[Mark Onofri]

The auto correct changed Bill's last name. It was Slitter,he always spoke very highly of you. Anyway, I should have listened to both of them