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Member postings for Brian Parker

Here is a list of all the postings Brian Parker has made in our forums. Click on a thread name to jump to the thread.

Thread: FP-R105M (Psst its actually a 7 channel!)
11/03/2010 13:50:36
It's probably just a generic board and it  will not be populated for the full channel spec.
Thread: Diesel v Glow
11/03/2010 13:41:21
In reality a British Invention, Patent No 7146 (The Compression Ignition Oil Engine) taken out by the British engineer Herbert Ackroyd-Stuart in 1890, a full two years before Dr Diesel’s coal dust fuelled engine.
By the way, as I understand it, a sub-induction piston engine is optimised to produce performance at high RPM (at the expense of poor low-end performance) and it is not designed to be throttled.
Not tried it IanN, but not sure you can actually fit as many silencing devices as you like with minimal impact on performance.
Thread: Finding a bright spark
05/03/2010 15:08:36
Further developments..... Adding auto advance.
 Obtaining a reliable, smooth operating mechanical system that tracks a correct timing curve is not easy (read almost impossible).
 Conventionally the throttle arm moves backwards and forwards and the advance lever moves left to right. For ease of connectivity they need to be in the same plane (pun sorry).
Best solution, use a PIC microprocessor, not difficult surely?
That’s what I thought.
 
The mock-up.

 
 

Students of Irony will appreciate the use of an electric motor to develop an IC operation.
Hall effect on arm detects magnet on rotating hub, white disc is stationary, cocktail stick in hub provides reference for counting RPM and yellow LED is visual indicator of output. The white object and small PCB on the right hand side of the scribing block simulates the coil and the ignition circuit. Prototype Vero board allows the programming of any 8-40 pin PIC microprocessors and also contains a 4Mhz crystal.
 Now all I need to do is to get my head round the program.
 

The best result I've managed so far.
Top trace (single pulse only shown) is hall input, lower trace is coil trigger/ignition point. This may take some time.
 
Thread: Which lathe ?
01/03/2010 15:37:03
I have had the SIEG C3 (from ARC Euro Trade) for some time, bought when they had their 'Fully loaded' offer on.
 More than satisfied with it although I have done a few modifications.
 It is a simple job to commission it yourself, you don’t need to pay ARC to do it, plus it gets you to know the workings of the lathe.
 If you havn't any tooling etc then expect to spend almost the same amount again to set yourself up properly if you want to be able build engines etc.
 Mine has proved to be very reliable, only needing a new drive belt (oil contamination due to over-enthusiastic lubricating) although it does need regular adjustment with use.
 The most noticeable modification is to fit the Brass Gibs set for instant smoothness.
The Book, 'The Mini-Lathe' by David Fenner takes you through the commissioning process, I wish it had been available when I bought mine. It details several modifications and has lots of useful information.
The Lathe is actually a Chinese copy of a Russian Lathe.
Thread: EDF current draw in the air
21/02/2010 15:47:25
I think the difference is between the pressure in a confined column and in a free surface/space.
Dynamic pressure is probably involved somewhere.
Thread: 2.4 is it rock solid ??
21/02/2010 15:18:34
By the description the system is a LAN and uses a multiple access coding key probably similar to bluetooth etc.
 A different access method to our system.
Thread: How do you balance a folding prop?
21/02/2010 15:16:59
Hang it by a thin cotton thread?
Thread: EDF current draw in the air
21/02/2010 10:04:42
Yes it’s a fan or an impeller in a tube and as indicated by my earlier post, air is a fluid and with the impeller stationary the pressure is equal on both sides.
 As we throttle up we are transferring the pressure.
 The thrust is caused by a change in momentum not by a change in energy (Newtons second law).
Therefore loading is relatively constant.
19/02/2010 17:50:31
At my age I've forgotten more than I ever knew but the answer probably lies in the transmissibility of fluid pressure and resultant thrust ie the difference between the thrusts/pressure on each side of the fan and its relationship to the total pressure. A graph/plot will show a straight line.
Thread: How low is low?
18/02/2010 17:23:37
A few years ago the A10s used to fly particularly low over the fells (and even lower over the lakes themselves).
 I've even ducked when in a kayak.
Thread: LiPos in cold weather
18/02/2010 17:10:17
I fail to see how operating at low temperatures can increase flying times.
 Low temperature and the resultant change in the rate of chemical activity causes the internal resistance of the battery to increase.
The lower the temperature the more the resistance.
 This reduces the self-discharge during storage but the efficiency will be reduced if the battery is used in this cold state.
Any warming during use will reduce the internal resistance thus restoring the efficiency but as extra energy was wasted (because of the higher resistance) during the cold usage the battery will reach its discharged state sooner.
Thread: How low is low?
17/02/2010 20:00:34

 
Just clearing Rosthwaite Fell from the Langstrath valley.
Thread: DSM2
11/02/2010 14:29:25
The DSSS system uses a unique encoding key for your transmitter/receiver.
 It transmits in short bursts and has an expanded bandwidth (spread spectrum).
 It is unaffected by noise and several systems can operate on the band simultaneously, your receiver will just ignore any signals without it's key.
The wanted information is recovered by the receiver in a dispreading operation. (The receiver is the clever part of the system).
I wouldn't worry about loosing both channels simultaneously, it just will not happen provided the system is correctly set up and used accordingly.
Thread: Scalextric Cars
01/02/2010 19:29:33
High and low pass filters in your crossovers Myron, they won't stop a well-worn Scalextric car running close-by at high speed from ruining your quality Hi.Fi. listening.
.
01/02/2010 14:27:11
 
These small motors and the method of supply are the most effective noise produces known to man, capable of producing noise spikes on both supply and 0V lines.
 I'ts been a long time since I looked at Scalextric and can't remember the actual setup. But,
 Firstly if there is not a capacitor across the motor terminals then fit a 1uf capacitor across the terminals (or a 0.1uf capacitor and a resistor in series will absorb and dissipate excess energy if required) then fit two 0.1uf capacitors, one on each motor terminal to the motor casing.
 If necessary also fit a 1uf capacitor across the track supply.
 Keep all leads as short as possible to reduce inductance.
Check that there is a diode across the controller supply lines (before any reversing switch) if not fitting one may prove beneficial.
 If you want to fit a ferrite cored choke, then fit a series 10 uH choke in the supply, but this souldn't be necessary at the frequencies involved.
 Try all or some of the above, good luck.
 Usual caveat.
Thread: Glow to Petrol Conversion.
31/01/2010 15:54:29
 
Tony,
It's from one of my many (unfinished) projects, a 1930s 50cc Rudge Whitworth Autocycle.
Doug,
It's not that difficult to make a plug although have not tried it myself.
Simon's Dad probably made the plugs for the V8 himself, I'm sure Simon will confirm.

Sorry even further off topic.

31/01/2010 14:12:53
And at the other end of the scale.
 

28/01/2010 15:47:35
Tony,
Is that not the Push Pull electronic distributorless system. It has two primary windings and a double-ended secondary in each coil with ignition amplifiers that switch the primary current electronically inducing the Push Pull.
Surly different from two HT from one coil.
28/01/2010 14:49:40
It would actually fire just before TDC so the Exhaust would be just closing and as/before the inlet opens. The spark would at the least clear the exhaust and silencer of any combustible residue.
If I recall, sparking the exhaust has been used in the past to tune exhaust pulses and to clean up exhaust emissions.
28/01/2010 12:09:16
You can't connect two HT cables to a single unit.
 One will always lead the other and fire the spark, as its virtually impossible to balance them electrically. Also the short spark duration of the CDI unit will not help.
 Plus I don’t think all Saito Twins have crankshafts that TDC both pistons at the same time. You need to be sure that you purchase the correct CDI unit(if available) for your engine configuration.
 In my (limited) experience the glow fuel carburettor's needle/jet combination is not really suitable for petrol. It needs to by reduced by at least 50% to allow finer adjustment to be made.
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