battery powered tube amplifier

by:CTECHi     2019-12-30
The tube amplifier is loved by guitar players due to its pleasant distortion.
The idea behind this instrument is to build a low wattage tube amplifier that can also be played with you on the go.
In the era of Bluetooth speakers, it\'s time to make some portable battery-powered tube amplifiers.
Because the power consumption of the tube amplifier is a huge problem, choosing the right tube can save a lot of power and increase the playback time between charging.
A long time ago, there were battery-powered tubes from small radio equipment to aircraft.
Their greatest advantage is the low filament current required.
The picture shows the three battery power supply tubes used in the Guitar Preamp, the comparison between 5672, 1j24b, 1j29b and the micro-tube, and the selected ef86 tube is:
13 mA wire current at 1. 2V, 120V max.
Plate voltage made in Russia, cheap price)Power: 1J29B (
32 mA wire current at 2. 4V, 150V max.
Plate voltage made in Russia, cheap price)
Cheaper transformers can be used for this low power setting.
Some experiments with line transformers show that they are very good for smaller amplifiers, because the bottom end is not a priority in these amplifiers.
Since there is no air gap, the transformer works better in pushing pressurepull.
This also requires more taps.
100V line transformer, 10w with different taps (0-10W-5W-2. 5W-1. 25W-0.
625W and 2 grades 4, 8 and 16 ohms).
Fortunately, the transformer I get also specifies the number of turns per winding, otherwise some math is needed to determine enough taps and the highest impedance available.
The transformer has the following laps at each tap (
Start from left):725-1025-1425-2025-
2925 in elementary school and 48-66-
Open Middle School 96.
You can see 2 here.
The 5w faucet is almost in the middle with 1425 switches on one side and 1500 switches on the other.
This tiny difference can be a problem in some of the larger amplifiers, but here it only increases distortion.
Now we can use 0 and 0.
625W tap for anode to get the highest impedance.
Using an 8 ohm speaker, the primary to secondary turn ratio is used to estimate that the primary impedance is: 2925/48 = 61, which gives 61 ^ 2*8 = 29768 or approximately. 29. 7k anode-to-
Anode2925/66 = 44, using an 8 ohm speaker, this gives 44 ^ 2*8 = 15488 or approximately. 15. 5k anode-to-
Anode2925/96 = 30, using an 8 ohm speaker, which gives 2*8 = 7200 or approximately. 7. 2k anode-to-
Since we intend to run this in class AB, we actually see that the impedance of the tube is only 1/4 of the calculated value.
Even this small tube needs to provide a higher voltage on the board.
Instead of using a few batteries in series or those huge old 45v batteries, I used a smaller switching power supply (SMPS)
Based on the MAX1771 chip.
With this SMPS, I can multiply the voltage of the battery by a value of up to 110V without any problems.
The battery selected for this project is Li-
Ion battery easily accessible in 186850 package.
There are several charging boards on line.
An important note is to purchase only known good batteries from trusted sellers to avoid unnecessary accidents.
Now that the parts have been roughly defined, it\'s time to start the circuit work.
A series of configurations have been selected to power the pipe wire.
Some difficulties must be discussed.
The thin wire scheme of the voltage looks like this: Battery (+)(8. 4V to 6V)-> 1J29b (6V)-
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